A material for carbon sliding plate for pantographs in rail transit and its preparation method

Abstract

The application discloses a material for a carbon slide plate of a pantograph of rail transit and a preparation method thereof. The material raw material comprises graphite powder, carbon powder, modified carbon fiber and boron modified phenolic resin; wherein, the graphite powder is 10-50 parts, the carbon powder is 20-50 parts, the modified carbon fiber is 5-30 parts, and the boron modified phenolic resin is 1-30 parts in terms of mass fraction; the modified carbon fiber comprises nickel-plated COFs modified carbon fiber; the nickel-plated COFs modified carbon fiber is adopted in the application, on one hand, a benzene ring structure can be introduced to the surface of the carbon fiber, since the main chain of the boron phenolic resin is mainly composed of benzene rings and methylene groups, the benzene ring on the surface of the carbon fiber can effectively improve the compatibility between the carbon fiber and the boron phenolic resin, based on the high hardness and compactness of the carbon fiber itself, combined with the stable friction coefficient and the oxidation resistance of the boron phenolic resin.

Description

Technical Field

[0001] This invention belongs to the field of carbon materials technology, specifically relating to a carbon sliding plate material for rail transit pantographs and its preparation method. Background Technology

[0002] Modern rail transit, including high-speed trains and urban rail transit, obtains traction power through the pantograph-catenary system on electric locomotives. The pantograph contact plate, a key component and major consumable part of the electric locomotive, is crucial to train operation safety and cost. Besides mechanical wear, the pantograph contact plate is also subject to frequent arcing. Therefore, it must possess excellent conductivity to ensure efficient current transmission; secondly, it should effectively suppress offline arcing and resist arc burns; thirdly, it must have excellent wear resistance to withstand prolonged high-speed sliding; fourthly, it must possess sufficient strength to adapt to complex and changing working environments; and fifthly, to reduce energy loss, it should have low resistivity and contact resistance. These performance requirements collectively constitute the core characteristics of the pantograph contact plate, enabling it to perform optimally in electric locomotives and ensuring safe and efficient train operation.

[0003] To improve the conductivity of pantograph sliders, the first thought is to add metallic conductive agents to the system. However, the carbon slider itself has non-interconnected pores. After adding metallic conductive agents, insufficient wettability will occur between the carbon phase and the metal phase. This will make it difficult for the metal phase to diffuse uniformly in the pores of the carbon slider blank. This will lead to problems such as insufficient conductivity, weak mechanical strength and poor resistance to arc erosion of the carbon slider.

[0004] Secondly, a pore-forming agent is added to the system. Patent CN 110436926 A uses brazing filler metal, copper, and a pore-forming agent to prepare an impregnated carbon pantograph slide plate blank. However, to improve the wettability between the carbon and copper phases, a strong external magnetic field is applied during the impregnation process, making the process relatively complex. Thirdly, carbon fiber is added. This is because carbon fiber has high strength and modulus, a negative coefficient of thermal expansion, and properties such as wear resistance, ablation resistance, and high electrical conductivity. Adding carbon fiber as a reinforcing agent to the pantograph slide plate can improve the bonding performance and interfacial bonding strength between the carbon fiber and other components within the slide plate, enhancing the slide plate's electrical conductivity, thermal conductivity, wear resistance, and impact toughness. It can also improve the slide plate's self-lubricating properties, strengthening its performance in high-speed railway operation. However, the smooth surface of carbon fiber is chemically inert, resulting in a weak interfacial bond between it and the resin matrix, making it difficult to achieve ideal wear resistance, electrical conductivity, and durability. Patent CN201710661308.4 uses nitric acid to oxidize carbon fibers, which improves the surface roughness and activity of the carbon fibers. However, the oxidation method inevitably damages the carbon fibers, leading to a decrease in their strength. In contrast, patent CN201310552131.6 uses nitrogen as a medium to generate low-temperature plasma on the carbon fiber surface, increasing the number of active functional groups and roughness of the carbon fiber surface through ion bombardment. While this treatment improves the interfacial bonding strength between the carbon fibers and the resin matrix, it is costly and difficult to control the reaction process and degree. Furthermore, the addition of carbon fibers not only reduces the density of the carbon pantograph and improves conductivity and strength, but also has the disadvantages of high cost and brittleness. Therefore, there is an urgent need to improve carbon fiber surface treatment technology or explore new interfacial reinforcement strategies to enhance its bonding force with the resin matrix, thereby further improving the wear resistance, durability, and conductivity of the pantograph pantograph.

[0005] To enhance the ablation resistance of pantograph contactors, besides adding ablation-resistant agents such as high-temperature resistant inorganic fillers and antioxidants to the pure carbon contactor to form a protective layer at high temperatures and reduce oxidation, thus improving the ablation resistance, phenolic resins or boron-modified phenolic resins with good heat and ablation resistance can also be added. Patent CN100365036 C uses a two-step method to prepare a high-boron phenolic resin, but the preparation process uses organic solvents, which not only increases costs but also adds complexity to the process. The organic solvents need to be removed later, and their flammable and explosive properties increase safety hazards during production. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0008] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a material for carbon sliding plates for pantographs in rail transit.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a material for a carbon sliding plate for a pantograph in rail transit, wherein the raw materials of the material include graphite powder, carbon powder, modified carbon fiber, and boron-modified phenolic resin; wherein, by mass parts, the graphite powder is 10-50 parts, the carbon powder is 20-50 parts, the modified carbon fiber is 5-30 parts, and the boron-modified phenolic resin is 1-30 parts.

[0010] The modified carbon fiber includes nickel-plated COFs modified carbon fiber.

[0011] As a preferred embodiment of the material described in this invention, the nickel-plated COFs modified carbon fiber is prepared by a method comprising:

[0012] The carbon fiber is calcined to remove the gel layer, thus obtaining pretreated carbon fiber.

[0013] Pretreated carbon fibers were immersed in a DMF solution containing amine compounds and reacted, and then dried to obtain carbon fibers loaded with amine compounds.

[0014] Carbon fibers loaded with amine compounds are immersed in a solution containing 1,4-dioxane, an aldehyde compound, to allow COF to polymerize and graft onto the surface of the carbon fibers in situ, thus obtaining modified carbon fibers grafted with COF.

[0015] The modified carbon fibers were washed with a dioxane solution to remove unreacted monomers.

[0016] COF-modified carbon fibers are immersed in an electroplating solution containing nickel salts. Through an electrochemical reaction, nickel ions are reduced to metallic nickel on the fiber surface to form a nickel plating layer, thus obtaining nickel-plated COF-modified carbon fibers.

[0017] In a preferred embodiment of the material described in this invention, the calcination temperature is 400–600°C.

[0018] As a preferred embodiment of the material described in this invention, the amine compound includes one of p-phenylenediamine (DB), benzylenediamine (BD), and 4,4-triphenylenediamine (Td); the aldehyde compound includes trimethylolpropane (TFB); and the in-situ polymerization conditions of COFs are ambient temperature and pressure, and the time is 2 to 5 days.

[0019] As a preferred embodiment of the material described in this invention, the electroplating solution containing nickel salt has the following specific composition:

[0020] The concentrations of NiSO4 are 35–240 g / L, NiCl2 is 20–120 g / L, and H3BO3 is 25–60 g / L.

[0021] The current density of the electrochemical reaction is 10–95 A / m 2 The electroplating time is 15-50 seconds.

[0022] In a preferred embodiment of the material described in this invention, the boron-modified phenolic resin is prepared by a method comprising:

[0023] Esterification stage: Phenol or cashew oil modified phenol and boric acid are weighed into a three-necked flask, a thermometer and a condenser are connected, the temperature is gradually increased to T1, the reaction time is t1, the dehydration time under reduced pressure is t2, the amount of dehydration is m1, and phenyl borate is synthesized.

[0024] The obtained phenyl borate was cooled to a temperature of T2;

[0025] The structure of phenyl borate is as follows:

[0026]

[0027] Synthetic thermosetting boron phenolic resin:

[0028] Paraformaldehyde was added to phenyl borate, and the temperature was gradually increased to T3 for a reaction time of t3. Distillation was carried out at atmospheric pressure for t4 and under reduced pressure for t5. The product was discharged as a yellow viscous oily substance, which was dried under reduced pressure in an oven at temperature T4 for t6 to obtain a yellow blocky solid.

[0029] As a preferred embodiment of the material described in this invention, the molar ratio of phenol or cashew oil-modified phenol to boric acid is 3:1, the reaction temperature T1 is 110-130℃, the reaction time t1 is 1-2h, the vacuum distillation dehydration time t2 is 2-3h, the mass ratio of dehydration amount m1 to phenol input is 7%-8%, and the cooling temperature T2 is 50-60℃.

[0030] The preferred molar ratio of paraformaldehyde to phenol or cashew oil-modified phenol is 1.05:1 to 1.3:1.

[0031] The reaction temperature T3 is 105–120°C;

[0032] The reaction time t3 is 0.5 to 1 hour;

[0033] The atmospheric pressure distillation dehydration time t4 is 0.5 to 1 hour;

[0034] The vacuum distillation dehydration time t5 is 1-2 hours;

[0035] The drying temperature T4 is 40–70°C;

[0036] The reaction time t6 is 36–60 h.

[0037] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a carbon sliding plate material for a pantograph in rail transit, comprising,

[0038] Graphite powder, carbon powder, modified carbon fiber, boron-modified phenolic resin and conductive agent are mixed and mixed evenly to obtain a mixture.

[0039] The mixed materials are processed and shaped to produce carbon sliding plates for pantographs in rail transit.

[0040] The conductive agents include copper nanowires and metallic copper powder.

[0041] As a preferred embodiment of the preparation method described in this invention, the processing and shaping includes,

[0042] If copper nanowires are used as a conductive agent, carbon slide plates can be prepared by kneading and sintering: the mixed materials are placed in a mold, the materials are tightly bound by kneading process, and then placed in a sintering furnace for sintering to form a hard carbon slide plate.

[0043] If copper powder is used as a conductive agent, carbon slide plates can be prepared by hot isostatic pressing: the mixed materials are placed in a mold, and then in a hot isostatic pressing equipment, the materials are tightly bonded by heating and high pressure to form a carbon slide plate.

[0044] As a preferred embodiment of the preparation method described in this invention, the pantograph slide plate is prepared by using copper nanowires as a conductive agent, with the amount of copper nanowires added being 1-5% of the total mass, and is prepared by kneading and sintering, with a sintering temperature of 1000-1500℃ and a sintering time of 120-960h.

[0045] Copper powder is used as a conductive agent, with the amount of copper powder added being 1-7% of the total mass. The hot isostatic pressing temperature is 1000-2000℃, the pressure is 50-500MPa, and the time is 120-840h.

[0046] Beneficial effects of this invention:

[0047] (1) This invention uses nickel-plated COFs modified carbon fiber as a conductive reinforcing material, which improves the conductivity and wear resistance of the carbon slide plate. By introducing boron-modified phenolic resin, the high temperature resistance and mechanical strength of the carbon slide plate are improved. At the same time, the use of nickel-plated COFs modified carbon fiber can introduce benzene ring structure on the surface of the carbon fiber. Since the main chain of boron phenolic resin is mainly composed of benzene ring and methylene, the benzene ring on the surface of the carbon fiber can effectively improve the compatibility between the carbon fiber and the boron phenolic resin. Based on the high hardness and density of the carbon fiber itself, combined with the stable friction coefficient and anti-oxidation properties of the boron phenolic resin, the effective combination of the two greatly improves the performance of the material (wear resistance, conductivity and mechanical properties). On the other hand, during the carbon slide plate molding process, the addition of nickel-plated COFs modified fiber will promote the interaction between the carbon fiber and the boron phenolic resin. The introduction of appropriate amounts of carbon fiber and metal elements can increase the starting temperature of the material curing reaction and reduce the activation energy of the reaction, thereby shortening the production cycle and improving the ablation resistance of the material.

[0048] (2) In this invention, covalent organic frameworks (COFs) are in situ polymerized and grafted onto the surface of carbon fibers to obtain COFs-grafted modified carbon fibers. The reaction can be carried out at room temperature and pressure, the process is relatively simple, and it is easy to achieve large-scale production. By electrochemical method, the COFs-grafted modified carbon fibers are nickel-plated, and the resulting nickel-plated COFs-modified carbon fibers have better conductivity.

[0049] (3) The boron-modified phenolic resin prepared by the present invention uses phenol or cashew oil-modified phenol, formaldehyde and boric acid as raw materials. The preparation method is mild and simple, with a short experimental cycle. No catalyst is used, and it can achieve large-scale synthesis. The boron-modified phenolic resin of the present invention has good high-temperature resistance. Through thermogravimetric analysis, the resin only shows obvious thermal decomposition at around 600℃, and the char residue at 1000℃ can still reach more than 62%.

[0050] (4) The present invention uses two process routes to prepare carbon slide plates. The appropriate process route can be selected according to actual needs to improve production efficiency and reduce costs. The process is simple, easy to operate, and the product performance is stable, which reduces manufacturing costs. The process design is reasonable, the process is simple, the operation is strong, and it has good application prospects. Attached Figure Description

[0051] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0052] Figure 1 The images shown are SEM images of the surface morphology of nickel-plated COFs modified carbon fibers in the embodiments of the present invention. Among them, (a) is the SEM image of COFs, (b) is the SEM image of carbon fibers before modification, and (c) and (d) are the SEM images of nickel-plated COFs fibers.

[0053] Figure 2 The infrared spectrum of boron-modified phenolic resin BP20 in this embodiment of the invention is shown.

[0054] Figure 3 The thermogravimetric curves of boron-modified phenolic resins BP20 and G4 in the embodiments of the present invention are shown. Detailed Implementation

[0055] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0056] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0057] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0058] In this embodiment of the invention, the graphite powder was purchased from Shanghai Kajite Chemical Technology Co., Ltd., with a graphite specification of 500 mesh; the toner was also purchased from Shanghai Kajite Chemical Technology Co., Ltd., with a specific surface area (BET) of 230 m². 2 / g.

[0059] The preparation process of cashew oil-modified phenol 1 in this embodiment of the invention is as follows:

[0060]

[0061] The above-mentioned raw material 1 (30 mg, 0.10 mmol) was added to a solution of 50% KOH (0.5 mL) and DMSO (1.5 mL), stirred at 80 °C for 1 h, cooled to room temperature, acidified with 2 M hydrochloric acid, and then extracted with ethyl acetate. The organic layer was dried over magnesium sulfate and concentrated under vacuum. The residue was purified by silica gel column chromatography with n-hexane / ethyl acetate (7:3) as eluent to give white solid 2 (25 mg, 96%).

[0062] 1H NMR (CDCl3, 400MHz): δ = 10.99 (s, 1H), 7.37 (t, 1H), 6.88 (d, 1H), 6.79 (d, 1H), 2.98 (t, 2H), 1.58-1.64 (m, 2H), 1.28-1.38 (m, 10H), 0.88 (t, 3H).

[0063] The stirred solution of 2 (218 mg, 0.87 mmol)-triethylamine (1:1 v / v) was stirred at 90 °C for a few minutes. Then, benzyl chloride (108 mg, 0.87 mmol) was added to the reaction mixture at 90 °C, and the mixture was stirred at 90 °C for another 1.5 h. After the reaction was completed, the reaction mixture was cooled to room temperature, acidified with 2 M hydrochloric acid, extracted with ethyl acetate, and dried in magnesium sulfate.

[0064] The organic layer was concentrated under vacuum to provide a residue, which was purified by silica gel column chromatography with n-hexane / ethyl acetate (9.25:0.75) to give a colorless oily compound (266 mg, 90%), namely cashew oil modified phenol 1.

[0065] 1H NMR (400MHz, CDCl3): δ=11.13(s,1H),7.37-7.31(m,4H),7.34-7.27(m,2H),6.91-6.86(m,1H),6.81(dd,1 H),5.53(d,2H),2.66(td,2H),1.65-1.55(m,2H),1.39-1.29(m,4H),1.32-1.25(m,6H),0.92-0.86(m,3H).

[0066] The preparation process of cashew oil-modified phenol 2 in this embodiment of the invention is as follows:

[0067]

[0068] Add the above raw material 1 (50 mg, 0.13 mmol) to 50% KOH (0.75 mL) and DMSO (2 mL), and stir at 80 °C for 1 h;

[0069] The reaction was cooled to room temperature, acidified with 2M hydrochloric acid, and then extracted with ethyl acetate.

[0070] The organic layer was dried with magnesium sulfate and concentrated under vacuum; the residue was purified by silica gel column chromatography with hexane / ethyl acetate (7:3) as eluent to give a white solid 2 (41 mg, 91%).

[0071] 1H NMR (CDCl3, 400MHz): δ = 11.13 (s, 1H), 7.37 (t, 1H), 6.88 (d, 1H), 6.73 (d, 1H), 3.00 (t, 2H), 1.59-1.65 (m, 2H), 1.29-1.34 (m, 24H), 0.89 (t, 3H).

[0072] A stirred solution of 2 (300 mg, 0.87 mmol)-triethylamine (1:1 v / v) was stirred at 90 °C for several minutes. Then, benzyl chloride (108 mg, 0.87 mmol) was added to the reaction mixture at 90 °C, and the mixture was stirred at 90 °C for another 1.5 h. After the reaction was complete, the reaction mixture was cooled to room temperature, acidified with 2 M hydrochloric acid, extracted with ethyl acetate, and dried in magnesium sulfate. The organic layer was concentrated under vacuum to provide a residue, which was purified by silica gel column chromatography with n-hexane / ethyl acetate (9.25:0.75) to give a colorless oily compound, namely cashew oil modified phenol 2 (351 mg, 92%).

[0073] 1 H NMR (400MHz, CDCl3): δ = 11.17 (s, 1H), 7.39-7.29 (m, 6H), 6.89-6.80 (m, 2H), 5.55 (d ,2H),2.69-2.64(m,2H),1.62-1.57(m,2H),1.36-1.27(m,24H),0.90-0.87(t,3H).

[0074] The raw materials used in both cashew oil modified phenol 1 and cashew oil modified phenol 2 were purchased from Changchun Aidi Technology Co., Ltd.

[0075] Example 1

[0076] (1) Preparation of nickel-plated COFs modified carbon fibers:

[0077] Weigh 65g of carbon fiber (Shanghai Kajite Chemical Technology Co., Ltd.), ignite it in a muffle furnace at 450℃ for 5 minutes, and remove the adhesive on the surface.

[0078] The degummed carbon fiber was immersed in a 0.15M p-phenylenediamine DMF solution and magnetically stirred for 5 hours at room temperature.

[0079] After drying, the carbon fibers loaded with p-phenylenediamine were immersed in a 0.1 M trimethylolpropionate solution of 1,4-dioxane, left to stand at room temperature for 3 days, and washed with dioxane 3 to 5 times.

[0080] Modified carbon fibers were immersed in an electrolyte containing 70 g / L NiSO4, 50 g / L NiCl2, and 30 g / L H3BO3, with the current density controlled at 45 A / m. 2 (DC, 5V), the electroplating process lasts for 20 seconds.

[0081] See SEM images of the surface morphology of nickel-plated COFs modified carbon fibers. Figure 1 Among them, (a) is the SEM image of COFs, (b) is the SEM image of carbon fiber before modification, and (c) and (d) are the SEM images of nickel-plated COFs carbon fiber.

[0082] (2) Preparation of boron-modified phenolic resin

[0083] ① Esterification stage: Phenol (500.00g, commercially available, Shanghai Maclean Biochemical Technology Co., Ltd.) and boric acid (109.12g) were weighed into a 1000mL three-necked flask, a thermometer and a condenser were connected, the temperature was gradually raised to 110℃ and reacted for 2 hours, and the phenyl borate was synthesized by vacuum distillation for 3 hours. The amount of water removed was about 40mL.

[0084] The obtained phenyl borate was cooled to a temperature of 80°C.

[0085] ② Condensation and Dehydration Stage

[0086] Synthesis of thermosetting boron phenolic resin: Paraformaldehyde (175.50g, commercially available, Shanghai Maclean Biochemical Technology Co., Ltd.) was added and the temperature was gradually raised to 120℃ and reacted for 0.5 hours. Then, it was distilled under normal pressure for 0.5 hours and then distilled under reduced pressure for about 1 hour. The product was discharged as a yellow viscous oily substance, which was dried under reduced pressure in an oven at 60℃ for 36 hours to obtain a yellow blocky solid BP20588 g, with a yield of 75%.

[0087] The prepared resin was formulated into a 50% ethyl acetate solution and used for bonding aluminum sheets. It was cured at 120℃, 150℃ and 180℃ for 2 hours each. The shear strength of the resin was tested according to standard GB / T 7124-2008, and its shear strength was 4.20 MPa.

[0088] The infrared spectrum of boron-modified phenolic resin BP20 is shown below. Figure 2 , of which: 3355cm -1 The absorption peak for the stretching vibration at -O is 1480 cm⁻¹. -1 The peak at 1385 cm⁻¹ represents the absorption peak of the double bond vibration of the benzene ring. -1 The absorption peak for the stretching vibration of BO is at 1220 cm⁻¹. -1 The absorption peak at 1100 cm⁻¹ is the phenolic hydroxyl group Ph-O. -1 The absorption peak at this point is the symmetric stretching vibration of the ether bond, indicating that boron-modified phenolic resin has been synthesized.

[0089] (3) Preparation of pantograph sliding plate for rail transit

[0090] Graphite powder, carbon powder, nickel-plated COFs modified carbon fiber, and boron-modified phenolic resin were mixed evenly in a mass ratio of 42:28:20:8.

[0091] Then add 2 parts by weight of copper nanowires (commercially available, Shanghai Kajite Chemical Technology Co., Ltd.) to the mixture, dry mix for 3 hours, and knead at 160°C.

[0092] The mixed material was then pressed into shape at 200 MPa and sintered under vacuum at 1200℃ for 480 h to obtain the desired carbon slide plate.

[0093] Example 2

[0094] (1) Preparation of nickel-plated COFs modified carbon fibers

[0095] The specific method is the same as in Example 1.

[0096] (2) Preparation of boron-modified phenolic resin

[0097] ① Esterification stage: Phenol (399.78g), cashew oil modified phenol 1 (361.56g) and boric acid (109.12g) were weighed into a 1000mL three-necked flask, a thermometer and a condenser were connected, the temperature was gradually raised to 110℃ and reacted for 2 hours, and the phenyl borate was synthesized by vacuum distillation for 3 hours. The amount of water removed was about 38mL.

[0098] The obtained phenyl borate was cooled to a temperature of 80°C.

[0099] ② Condensation and Dehydration Stage

[0100] Synthesis of thermosetting boron phenolic resin: Paraformaldehyde (175.50 g) was added and the temperature was gradually raised to 120 °C and reacted for 0.5 hours. Then, it was distilled under normal pressure for 0.5 hours and then distilled under reduced pressure for about 1 hour. The product was discharged as a yellow viscous oily substance. It was dried under reduced pressure in an oven at 60 °C for 36 hours to obtain a yellow blocky solid G4732 g, with a yield of 70%.

[0101] The prepared resin was formulated into a 50% ethyl acetate solution and used for bonding aluminum sheets. It was cured at 120℃, 150℃ and 180℃ for 2 hours each. The shear strength of the resin was tested according to standard GB / T 7124-2008, and its shear strength was 3.94 MPa.

[0102] Thermogravimetric curves of boron-modified phenolic resins BP20 and G4 are shown below. Figure 3It can be seen that the resin only undergoes significant thermal decomposition at around 600℃, and the char residue rate at 1000℃ can still reach more than 62%, indicating that the introduction of BO bonds improves the heat resistance of the resin.

[0103] (3) Preparation of pantograph sliding plate for rail transit

[0104] Graphite powder, carbon powder, nickel-plated COFs modified carbon fiber and boron-modified phenolic resin were mixed at 150°C for 120 min in a mass ratio of 40:30:20:10.

[0105] Then, the semi-finished product is obtained by extrusion at 220°C, and the semi-finished product is baked at 1250°C to obtain the porous carbon slide plate blank.

[0106] By means of hot isostatic pressing, 1 part by mass of metallic copper powder is impregnated into the porous blank of carbon slide plate at 1000℃ and 150MPa for 600h, filling the pores and forming a conductive network.

[0107] Finally, the impregnated carbon slide plate is ground and polished to obtain the final pantograph carbon slide plate.

[0108] Example 3

[0109] (1) Preparation of nickel-plated COFs modified carbon fibers

[0110] Weigh 90g of carbon fiber and ignite it in a muffle furnace at 550℃ for 5 minutes to remove the adhesive on the surface.

[0111] The degummed carbon fiber was immersed in a 0.15M benzidine DMF solution and magnetically stirred for 5 hours at room temperature.

[0112] After drying, the carbon fibers loaded with benzidine were immersed in a solution of 1,4-dioxane containing 0.1M pyromellitic methyl ether and left to stand at room temperature for 4 days.

[0113] The modified carbon fibers were washed 3-5 times with dioxane and then immersed in an electrolyte solution containing 120 g / L NiSO4, 75 g / L NiCl2, and 35 g / L H3BO3, with the current density controlled at 60 A / m. 2 The electroplating process lasts for 35 seconds.

[0114] (2) Preparation of boron-modified phenolic resin

[0115] ① Esterification stage: Phenol (399.78g), cashew oil modified phenol 1 (361.56g) and boric acid (109.12g) were weighed into a 1000mL three-necked flask, a thermometer and a condenser were connected, the temperature was gradually raised to 110℃ and reacted for 2 hours, and the phenyl borate was synthesized by vacuum distillation for 3 hours. The amount of water removed was about 38mL.

[0116] The obtained phenyl borate was cooled to a temperature of 80°C.

[0117] ② Condensation and dehydration stage: Synthesis of thermosetting boron phenolic resin: Paraformaldehyde (175.50g) was added and the temperature was gradually raised to 120℃ and reacted for 0.5 hours. Then, it was distilled under normal pressure for 0.5 hours and then distilled under reduced pressure for about 1 hour. The product was discharged as a yellow viscous oily substance. It was dried under reduced pressure in an oven at 60℃ for 36 hours to obtain 732g of yellow blocky solid, with a yield of 70%.

[0118] The prepared resin was formulated into a 50% ethyl acetate solution and used for bonding aluminum sheets. It was cured at 120℃, 150℃ and 180℃ for 2 hours each. The shear strength of the resin was tested according to standard GB / T 7124-2008, and its shear strength was 3.94 MPa.

[0119] (3) Preparation of pantograph sliding plate for rail transit

[0120] Graphite powder, carbon powder, nickel-plated COFs modified carbon fiber and boron-modified phenolic resin were mixed evenly in a mass ratio of 40:30:19:9.

[0121] Then, 2 parts by mass of copper nanowires were added to the mixture and dry-mixed for 3.5 hours.

[0122] Mix at 165℃ until the material is homogeneous;

[0123] The mixed material was pressed into shape under 250 MPa and vacuum sintered at 1300℃ for 360 h to obtain the desired carbon slide plate.

[0124] Example 4

[0125] (1) Preparation of nickel-plated COFs modified carbon fibers:

[0126] For details on the specific method, please refer to Example 3(1).

[0127] (2) Preparation of boron-modified phenolic resin:

[0128] For details on the specific method, please refer to Example 1(2).

[0129] (3) Preparation of pantograph sliding plate for rail transit:

[0130] Graphite powder, carbon powder, nickel-plated COFs modified carbon fiber, and boron-modified phenolic resin were mixed at 165°C for 110 min in a mass ratio of 41:29:20:8.

[0131] Then, the semi-finished product is obtained by extrusion at 220℃, and the semi-finished product is baked at 1300℃ to obtain the porous carbon slide plate blank.

[0132] By using hot isostatic pressing, 2 parts by mass of metallic copper powder were impregnated into the porous carbon slide plate blank at 1300℃ and 200MPa for 312 hours to fill the pores and form a conductive network.

[0133] Finally, the impregnated carbon slide plate is ground and polished to obtain the pantograph carbon slide plate.

[0134] Example 5

[0135] (1) Preparation of nickel-plated COFs modified carbon fibers:

[0136] For details on the specific method, please refer to Example 1(1).

[0137] (2) Preparation of boron-modified phenolic resin:

[0138] ① Esterification stage: Phenol (399.78g), cashew oil-modified phenol 2 (455.13g), and boric acid (109.12g) were weighed into a 1000mL three-necked flask. A thermometer and a condenser were connected, and the temperature was gradually raised to 120℃ for 2 hours. The mixture was then dehydrated by vacuum distillation for 2 hours to synthesize phenyl borate, with a dehydration volume of approximately 38mL. The obtained phenyl borate was cooled to 70℃.

[0139] ② Condensation and dehydration stage:

[0140] Synthesis of thermosetting boron phenolic resin: Formaldehyde (191.40g) was added and the temperature was gradually raised to 110℃ and reacted for 1 hour. Then, it was distilled under normal pressure for 1 hour and then under reduced pressure for about 1.5 hours. The product was discharged as a yellow viscous oily substance. It was dried under reduced pressure in an oven at 50℃ for 48 hours to obtain 866g of yellow blocky solid, with a yield of 75%.

[0141] (3) Preparation of pantograph sliding plate for rail transit

[0142] The graphite powder, carbon powder, nickel-plated COFs modified carbon fiber, and boron-modified phenolic resin were mixed evenly according to the mass ratio of 43:27:7:3 to obtain the mixture.

[0143] Then add 3 parts by weight of copper nanowires to the mixture and dry mix for 4 hours;

[0144] Mix at 170℃ until the material is homogeneous;

[0145] The mixed material was pressed into shape under 235 MPa and vacuum sintered at 1400℃ for 288 h to obtain the desired carbon slide plate.

[0146] Example 6

[0147] (1) Preparation of carbon fiber

[0148] Weigh 70g of carbon fiber and ignite it in a muffle furnace at 500℃ for 5 minutes to remove the adhesive on the surface.

[0149] (2) Preparation of boron-modified phenolic resin

[0150] For details on the specific method, please refer to Example 1(2).

[0151] (3) Preparation of pantograph sliding plate for rail transit

[0152] The graphite powder, carbon powder, pretreated carbon fiber, and boron-modified phenolic resin were mixed evenly according to a mass ratio of 41:29:18:10 to obtain a mixture.

[0153] Copper nanowires were added to the mixture, wherein the mass of the copper nanowires accounted for 2% of the mixture, and the dry mixing time was 4 hours.

[0154] Mix at 175℃ until the material is homogeneous;

[0155] The mixed material was pressed into shape under 230 MPa and vacuum sintered at 1250℃ for 408 h to obtain carbon slide plate.

[0156] Example 7

[0157] (1) Preparation of nickel-plated COFs modified carbon fibers

[0158] For details on the specific method, please refer to Example 1(1).

[0159] (2) Preparation of boron-modified phenolic resin

[0160] For details on the specific method, please refer to Example 5(2).

[0161] (3) Preparation of pantograph sliding plate for rail transit

[0162] Graphite powder, carbon powder, nickel-plated COFs modified carbon fiber, and boron-modified phenolic resin were mixed at 175°C for 105 min according to a mass ratio of 45:25:16:11. The mixture was then extruded at 230°C to obtain a semi-finished product. The semi-finished product was baked at 1350°C to obtain a porous carbon slide plate blank. Three parts by mass of copper powder were impregnated into the porous carbon slide plate blank by hot isostatic pressing at 1500°C and 250 MPa for 240 h to form a conductive network inside the carbon slide plate. Finally, the impregnated carbon slide plate was ground and polished to obtain the pantograph carbon slide plate.

[0163] Comparative Example 1

[0164] The American Hoffman pure carbon skateboard was used as a comparative example 1.

[0165] Comparative Example 2

[0166] A British Morgan metal-coated carbon skateboard was used as a comparative example 2.

[0167] Comparative Example 3

[0168] A German Panshuak metal-coated carbon skateboard was used as a comparative example 3.

[0169] Comparative Example 4

[0170] Graphite powder and boron-modified phenolic resin were mixed at 170°C for 115 minutes in a mass ratio of 50:30, and then extruded at 230°C to obtain a semi-finished product. The semi-finished product was baked at 1250°C to obtain a porous carbon slide plate blank. By hot isostatic pressing, 3 parts by mass of copper powder were impregnated into the porous carbon slide plate blank at 1350°C and 230MPa for 240 hours, so that the copper powder formed a conductive network inside the carbon slide plate. Finally, the impregnated carbon slide plate was ground and polished to obtain the pantograph carbon slide plate.

[0171] Comparative Example 5

[0172] (1) Preparation of carbon fiber:

[0173] Weigh 65g of carbon fiber and calcine it in a muffle furnace at 450℃ for 5 minutes to remove the surface adhesive and obtain the pretreated carbon fiber.

[0174] (2) Preparation of boron-modified phenolic resin:

[0175] The specific preparation process is the same as in Example 1.

[0176] (3) Preparation of pantograph sliding plate for rail transit:

[0177] The graphite powder, carbon powder, pretreated carbon fiber and boron-modified phenolic resin were mixed evenly in a mass ratio of 42:28:20:8.

[0178] Then add 2 parts by mass of copper nanowires to the mixture, dry mix for 3 hours, and knead at 160℃.

[0179] The mixed material was then pressed into shape at 200 MPa and sintered under vacuum at 1200℃ for 480 h to obtain the desired carbon slide plate.

[0180] Comparative Example 6

[0181] (1) Preparation of boron-modified phenolic resin: Same as in Example 1.

[0182] (2) Preparation of pantograph sliding plate for rail transit:

[0183] Graphite powder and boron-modified phenolic resin were mixed evenly in a mass ratio of 70:28.

[0184] Then add 2 parts by mass of copper nanowires to the mixture, dry mix for 3 hours, and knead at 160℃.

[0185] The mixed material was then pressed into shape at 200 MPa and sintered under vacuum at 1200℃ for 480 h to obtain the desired carbon slide plate.

[0186] The pantograph plates prepared in the above embodiments and comparative examples were subjected to performance tests. The relevant testing standards are: GB / T 34572-2017, GB / T 38955-2020, GTCC-010-2020, JBT 8133.1-2013, JBT 8133.14-2013, TB / T 1842.2-2016, TBT 1842.1-2002, TJ-CL-328-2013, TJ-CL-328-2014, DIN IEC60413. The test data are shown in Table 1.

[0187] Table 1 Performance Test Table of Pantograph Sliding Plate in Examples and Comparative Cases

[0188]

[0189]

[0190] This invention utilizes nickel-plated COFs-modified carbon fibers. On one hand, it introduces benzene ring structures onto the surface of the carbon fibers. Since the main chain of boron phenolic resin is primarily composed of benzene rings and methylene groups, the benzene rings on the carbon fiber surface can effectively improve the compatibility between the carbon fibers and the boron phenolic resin. Based on the high hardness and density of the carbon fibers themselves, combined with the stable friction coefficient and antioxidant properties of the boron phenolic resin, the effective combination of the two significantly enhances the material's performance. On the other hand, during the carbon slide molding process, the addition of nickel-plated COFs-modified fibers promotes the interaction between the carbon fibers and the boron phenolic resin. The introduction of appropriate amounts of carbon fibers and metal elements can increase the starting temperature of the material's curing reaction and reduce the activation energy of the reaction, thereby shortening the production cycle and improving the material's ablation resistance.

[0191] This invention provides a material for carbon sliding plate of pantograph for rail transit and its preparation method, in order to solve the problems of low conductivity and poor ablation resistance of pantograph sliding plate.

[0192] Carbon-based free radicals (COFs) are a class of crystalline porous organic polymers with permanent porosity and highly ordered structures. They are constructed through strong covalent bonds, exhibiting high thermal stability, high surface area, and extremely low density. COFs contain imino groups (-NH-), which can act as coordinating groups, forming stable coordinate bonds with various metal ions. This invention modifies carbon fibers with COFs, and then further electrochemically treats the modified carbon fibers to obtain nickel plating, combining the high specific surface area and excellent chemical stability of COFs with the high conductivity of nickel metal.

[0193] The porous structure and highly ordered crystalline properties of COFs play a crucial role in the modification of carbon fibers. These properties enable the formation of a continuous channel structure between the COFs and the carbon fibers. Further electrochemical nickel plating further strengthens these channels, creating a tight connection between the materials and forming a continuous pore network. This structural transformation significantly enhances the electrical conductivity of the modified carbon fibers, giving them superior conductivity. Adding nickel-plated COFs (covalent organic frameworks) to the system effectively reduces resistivity and improves the electrical conductivity of the pantograph contactor. This modified material not only retains the lightweight properties of carbon materials but also increases surface hardness and wear resistance through nickel plating, thereby improving overall mechanical properties and durability. Incorporating these into the pantograph contactor enhances the conductivity of the carbon contactor. In high-speed trains, pantograph contactors frequently face electrical ablation and wear caused by offline arcing, which severely affects the contactor's service life and the safe and stable operation of the train.

[0194] To enhance the heat resistance and ablation resistance of the pantograph contactor, this invention uses boron-modified phenolic resin as a binder, added to the contactor to effectively resist high temperatures and arc erosion, extending its service life. The boron-modified phenolic resin is prepared using a solid-phase generation method, eliminating the need for solvents and catalysts. This not only reduces environmental pollution during production but also effectively avoids potential side reactions and impurities, resulting in a high-purity product. The reaction conditions are mild, the production process is simple, efficient, and low-cost, making it suitable for large-scale production.

[0195] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A material for a carbon slide plate of a rail transit pantograph, characterized in that: The material raw material includes graphite powder, carbon powder, modified carbon fiber and boron modified phenolic resin; wherein, the graphite powder is 10-50 parts, the carbon powder is 20-50 parts, the modified carbon fiber is 5-30 parts and the boron modified phenolic resin is 1-30 parts in mass fraction; The modified carbon fiber includes nickel-plated COFs modified carbon fiber, and a preparation method of the nickel-plated COFs modified carbon fiber includes removing a gel layer of carbon fiber after calcination to obtain pretreated carbon fiber; The pretreated carbon fiber is soaked in a DMF solution containing an amine compound to react, and after drying, the carbon fiber loaded with the amine compound is obtained; The carbon fiber loaded with the amine compound is soaked in a solution containing an aldehyde compound in 1,4-dioxane to make COFs in-situ polymerize on the surface of the carbon fiber, thereby obtaining COFs grafted modified carbon fiber; The modified carbon fiber is washed with a dioxane solution to remove unreacted monomers; The COFs modified carbon fiber is immersed in an electroplating solution containing a nickel salt, and through electrochemical reaction, nickel ions are reduced to metallic nickel on the surface of the fiber to form a nickel plating layer, thereby obtaining the nickel-plated COFs modified carbon fiber; The amine compound includes one of p-phenylenediamine (DB), biphenyl diamine (BD) and 4, 4-triphenyl diamine (Td); the aldehyde compound includes triformylphenyl (TFB); and the in-situ polymerization condition of COFs is normal temperature and pressure, and the time is 2-5 days.

2. The material of claim 1, wherein: The calcination temperature is 400-600 DEG C.

3. The material of claim 1, wherein: The electroplating solution containing the nickel salt has specific components as follows: The concentration of NiSO4 is 35-240 g / L, the concentration of NiCl2 is 20-120 g / L, and the concentration of H3BO3 is 25-60 g / L; The current density of the electrochemical reaction is 10-95 A / m 2 ; and the plating time is 15-50 s.

4. The material of claim 1, wherein: The preparation method of the boron modified phenolic resin includes, An esterification stage: phenol or cashew oil modified phenol and boric acid are weighed in a three-necked flask, a thermometer and a condenser are connected, the temperature is gradually increased to T1, the reaction time is t1, the dehydration time is t2 under reduced pressure, the dehydration amount is m1, and boric acid phenyl ester is synthesized; The obtained boric acid phenyl ester is cooled, and the temperature is reduced to T2; The structure of the boric acid phenyl ester is as follows: Synthesis of thermosetting boron phenol formaldehyde resin: Polyformaldehyde is added to the boric acid phenyl ester, the temperature is gradually increased to T3, the reaction time is t3, the dehydration time is t4 under normal pressure, the dehydration time is t5 under reduced pressure, yellow viscous oil is obtained, and the yellow block solid is obtained by drying in an oven at a temperature of T4 under reduced pressure for t6 hours.

5. The material of claim 4, wherein: The molar ratio of phenol or cashew oil modified phenol to boric acid is 3:1, the reaction temperature T1 is 110-130 DEG C, the reaction time t1 is 1-2 h, the dehydration time t2 under reduced pressure is 2-3 h, the mass ratio of the dehydration amount m1 to the amount of phenol is 7%-8%, and the cooling temperature T2 is 50-60 DEG C; The molar ratio of polyformaldehyde to phenol or cashew oil modified phenol is 1.05:1-1.3:1; The reaction temperature T3 is 105-120 DEG C; The reaction time t3 is 0.5-1 h; The dehydration time t4 under normal pressure is 0.5-1 h; The dehydration time t5 under reduced pressure is 1-2 h; The drying temperature T4 is 40-70 DEG C; The reaction time t6 is 36-60 h.

6. A method of producing the material according to any one of claims 1 to 5, characterized in that: ​ The graphite powder, carbon powder, modified carbon fiber, boron modified phenolic resin and conductive agent are mixed to obtain a mixture; The mixture is processed to form a rail transit pantograph carbon slide plate; The conductive agent includes copper nanowires and copper powder.

7. The production method according to claim 6, characterized by: The processing includes, If the copper nanowires are used as the conductive agent, the carbon slide plate is prepared by mixing and sintering: the mixed material is placed in a mold, the material is tightly combined by mixing and kneading, and then is placed in a sintering furnace for sintering, so that the material forms a hard carbon slide plate; If the copper powder is used as the conductive agent, the carbon slide plate is prepared by hot isostatic pressing: the mixed material is placed in a mold, and then is tightly combined by heating and high pressure in a hot isostatic pressing device to form a carbon slide plate.

8. The production method according to claim 6, characterized by: The copper nanowires are used as the conductive agent, the addition amount of the copper nanowires is 1-5% of the total mass, the mixing and sintering method is used for preparation, the sintering temperature is 1000-1500℃, and the sintering time is 120-960h; The copper powder is used as the conductive agent, the addition amount of the copper powder is 1-7% of the total mass, the temperature of the hot isostatic pressing is 1000-2000℃, the pressure is 50-500MPa, and the time is 120-840h.

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