Polysilazane-graphene composite electrical equipment insulating and voltage-resistant protective coating and preparation method thereof

Abstract

The invention relates to the technical field of coatings, and discloses a polysilazane-graphene composite electrical equipment insulating and pressure-resistant protective coating and a preparation method thereof. The flame-retardant coating is prepared from the following raw materials in parts by mass: 30 to 50 parts of polysilazane, 3 to 5 parts of telomer, 1 to 3 parts of synergist, 4 to 5 parts of modified silicon dioxide, 4 to 5 parts of modified graphene, 1.5 to 2 parts of multiwalled carbon nanotube, 0.5 to 2 parts of modified zinc oxide, 1 to 2 parts of fluorocarbon surfactant and 130 to 230 parts of tetrahydrofuran. By introducing the telomer, the adhesive force of the coating on a rusty surface is effectively improved, and the properties of high temperature resistance, insulation and pressure resistance, flame retardance, water resistance, ice condensation resistance and the like are enhanced; by introducing the synergist, the modified silicon dioxide, the modified graphene, the multi-walled carbon nanotubes and the modified zinc oxide, the protection capability is further improved. Therefore, the coating disclosed by the invention is excellent in comprehensive protection performance, can meet the long-term operation requirement of power equipment in a complex and severe environment, and is wide in application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a polysilazane-graphene composite insulating and voltage-resistant protective coating for electric power equipment and a preparation method thereof. Background Art

[0002] In power systems, metal ancillary facilities closely associated with power equipment are constantly exposed to complex and changing environments. Outdoors, they are subject to wind, rain, sun, and the thermal expansion and contraction caused by the diurnal temperature swing. In tunnels, the damp, dark, and poorly ventilated operating environment makes metal facilities more susceptible to corrosion. Furthermore, the electromagnetic environment generated by power cables during operation can adversely affect metal ancillary facilities. These multiple factors combine to cause rapid corrosion of metal ancillary facilities.

[0003] The corrosion of metal facilities should not be underestimated. It not only endangers the safe and stable operation of cables, leading to serious consequences such as power transmission interruptions and equipment damage, but also poses a potential threat to the personal safety of operators. For example, rusted metal parts may suddenly break, resulting in casualties.

[0004] To address the corrosion problem of metal facilities, technicians have previously used hot-dip galvanizing. However, this method not only produces wastewater, exhaust gas, and solid waste, but also hazardous waste such as zinc ash, zinc slag, and even cyanide solution, posing significant environmental risks. Furthermore, once the galvanized coating on metal components is depleted, it cannot be replenished and must be replaced, resulting in significant waste. Furthermore, this anti-corrosion method has a short lifespan and cannot guarantee long-term effectiveness.

[0005] Given the numerous issues with hot-dip galvanizing, relevant technicians have proposed applying protective coatings to protect metal components. Compared to hot-dip galvanizing, protective coatings can, to a certain extent, provide waterproofing for metal components, blocking moisture intrusion and slowing the rate of metal corrosion. However, in practical application, existing protective coatings still have many shortcomings. On the surfaces of rusted metal accessories, protective coatings have poor adhesion and are prone to flaking, failing to form an effective protective barrier. Under long-term high-temperature operating conditions, the coatings are prone to cracking, further reducing adhesion, exposing metal components to harsh environments and accelerating corrosion. Furthermore, existing protective coatings' performance in terms of insulation, voltage resistance, flame retardancy, waterproofing, anti-icing, and corrosion resistance falls short of meeting the actual requirements of power equipment. For example, in the event of overvoltage conditions such as lightning, insufficient insulation performance can cause equipment breakdown; in the event of a fire, poor flame retardancy can exacerbate the spread of the fire; in humid environments, insufficient waterproofing and anti-icing properties can cause ice to form on the equipment surface, affecting normal operation; and in corrosive environments, poor corrosion resistance can shorten the equipment's service life. Therefore, the existing protective coatings for power equipment still need to be further improved in terms of rust surface adhesion, high temperature resistance, insulation and pressure resistance, flame retardancy, waterproof and anti-icing capabilities, and corrosion resistance. Summary of the Invention

[0006] The purpose of the present invention is to provide a polysilazane-graphene composite insulating voltage-resistant protective coating for power equipment and a preparation method thereof, to solve the following technical problems: Existing protective coatings for power equipment still have problems with poor rust surface adhesion, high temperature resistance, insulation and pressure resistance, flame retardancy, waterproof and anti-icing capabilities, and corrosion resistance.

[0007] The purpose of the present invention can be achieved through the following technical solutions: A polysilazane-graphene composite insulating and voltage-resistant protective coating for power equipment comprises the following raw materials in parts by mass: 30-50 parts of polysilazane, 3-5 parts of telomer, 1-3 parts of synergist, 4-5 parts of modified silicon dioxide, 4-5 parts of modified graphene, 1.5-2 parts of multi-walled carbon nanotubes, 0.5-2 parts of modified zinc oxide, 1-2 parts of fluorocarbon surfactant, and 130-230 parts of tetrahydrofuran.

[0008] Preferably, the preparation method of the telomer is as follows: A1: Methylamineethanol was added dropwise to acryloyloxytriisopropylsilane at 0-2°C under an argon atmosphere while stirring. After stirring for 2-3 hours, tetrahydrofuran and triethylamine were added at 0-2°C, and acryloyl chloride was added dropwise. After reacting for 6-8 hours, the mixture was filtered and the filtrate was evaporated to remove tetrahydrofuran. Ethyl acetate was then added and stirred for 30-60 minutes. Finally, the mixture was extracted with a saturated sodium chloride solution, and the ethyl acetate layer was dried over sodium sulfate. The mixture was filtered and concentrated to obtain a prepolymer. A2: Mix dodecafluoroheptyl methacrylate, prepolymer, silane coupling agent KH580, azobisisobutyronitrile, and tetrahydrofuran, and stir under a nitrogen atmosphere at 65-70°C for 24-30 hours. Then pour into hexane at -30-20°C, stir for 10-20 minutes, filter, and vacuum dry at 23-27°C for 12-20 hours to obtain a telomer.

[0009] Preferably, the usage ratio of acryloxytriisopropylsilane, methylamineethanol, tetrahydrofuran, triethylamine, acryloyl chloride, and ethyl acetate in A1 is 16-22.8 g: 5.2-7.5 g: 105-150 mL: 7.8-11.1 g: 7-10 g: 35-50 mL; The usage ratio of dodecafluoroheptyl methacrylate, prepolymer, silane coupling agent KH580, azobisisobutyronitrile, tetrahydrofuran, and hexane in A2 is 4.5-5.6 g: 4-5 g: 0.4-0.5 g: 0.045-0.056 g: 12-15 mL: 80-100 mL.

[0010] Preferably, the preparation method of the synergist is as follows: B1: Add lithium fluoride to the hydrochloric acid aqueous solution and stir for 20-30 minutes, then add titanium aluminum carbide and stir for 45-50 hours, centrifuge and wash the precipitate with deionized water 5-7 times, and finally vacuum dry at 55-60°C for 12-15 hours to obtain pretreated nanosheets; B2: Adjust the pH of the phytic acid aqueous solution to 7 with 25% ammonia water, then add the pretreated nanosheets and grind for 12-15 hours, then rotary evaporate to 40-50 mL at 85-90 ° C to obtain the synergist.

[0011] Preferably, the ratio of the hydrochloric acid aqueous solution, lithium fluoride, and titanium aluminum carbide in B1 is 200-300 mL: 10-15 g: 10-15 g; The concentration of the hydrochloric acid aqueous solution in B1 is 9 mol / L; The ratio of the phytic acid aqueous solution and the pretreated nanosheets in B2 is 190-240 mL: 10-13 g; The mass fraction of the phytic acid aqueous solution in B2 is 50%-60%.

[0012] Preferably, the preparation method of the modified silicon dioxide is as follows: Add hydrophobic silica nanoparticles to toluene and ultrasonically disperse for 30-60 minutes, then add triethylamine and stir under a nitrogen atmosphere for 20-30 minutes, add a toluene solution of heptafluorodecyltrichlorosilane and stir for 18-20 hours, centrifuge and wash the precipitate with dilute hydrochloric acid, deionized water, anhydrous ethanol and toluene 3-5 times respectively, and vacuum dry at 50-60° C. for 3-5 hours to obtain modified silica; The usage ratio of toluene, hydrophobic silica nanoparticles, triethylamine, and toluene solution of heptadecafluorodecyltrichlorosilane is 100-120 mL: 5-6 g: 1-1.2 mL: 20-24 mL; The concentration of the toluene solution of heptafluorodecyltrichlorosilane is 0.01 mol / L.

[0013] Preferably, the preparation method of the modified graphene is as follows: Graphene oxide was added to deionized water and ultrasonically treated for 30-60 minutes. The pH was then adjusted to 8-9 with 25% ammonia water. Silane coupling agent KH580 was then added and stirred at 40-45°C for 12-15 hours. The precipitate was washed 3-5 times with anhydrous ethanol after centrifugation and finally vacuum dried at 85-90°C for 6-12 hours to obtain modified graphene. The mass ratio of the deionized water, graphene oxide, and silane coupling agent KH580 is 100-120:5-10:0.2-0.4.

[0014] Preferably, the preparation method of the modified zinc oxide is as follows: Add octadecyl phosphate to toluene and stir at 55-60°C for 30-60 minutes. Then add zinc oxide nanorods and stir at 1000-1200 r / min at 55-60°C in a nitrogen atmosphere for 12-15 hours. After cooling to 20-40°C, centrifuge and wash the precipitate with anhydrous ethanol and toluene 3-5 times respectively, and then vacuum dry at 55-60°C for 6-10 hours to obtain modified zinc oxide.

[0015] Preferably, the usage ratio of toluene, octadecyl phosphate, and zinc oxide nanorods is 80-100 mL: 0.8-1 g: 1.6-2 g.

[0016] A method for preparing a polysilazane-graphene composite insulating and voltage-resistant protective coating for power equipment comprises the following steps: S1: adding modified silica, modified graphene, multi-walled carbon nanotubes, modified zinc oxide, and a fluorocarbon surfactant to tetrahydrofuran and performing ultrasonic dispersion at a power of 600-700 W for 60-90 min at 5-10° C., and filtering through a filter membrane with a pore size of 0.8 μm to obtain a mixed dispersion; S2: Add polysilazane and telomer to the mixed dispersion and stir for 1-2 hours, then add synergist and stir at 1000-1500 r / min for 30-60 minutes to obtain a polysilazane-graphene composite insulating voltage-resistant protective coating for power equipment.

[0017] Beneficial effects of the present invention: The present invention provides an industrial flue gas denitrification filter bag and a preparation method thereof. The present invention effectively improves the rust surface adhesion, high temperature resistance, insulation and pressure resistance, flame retardancy, waterproof and anti-icing ability, and corrosion resistance of the protective coating of power equipment through the following method.

[0018] (1) The present invention introduces modified silica: the surface organic fluorocarbon chain can improve the compatibility with the organic matrix and enhance the adhesion; it serves as a high-temperature resistant skeleton to enhance thermal stability, reduce thermal oxidative decomposition, and delay thermal aging; it fills microscopic pores, reduces dielectric loss, and enhances insulation strength and breakdown voltage; it forms an inorganic skeleton at high temperatures to block heat and oxygen, and the fluorine-containing groups inhibit the combustion chain reaction and enhance flame retardancy; the superhydrophobic property enhances water resistance and reduces ice condensation problems; the hydrophobicity blocks water, oxygen and corrosive ions, the fluorine-containing groups are resistant to chemical corrosion, and the nanosheet structure forms a "maze effect" to enhance corrosion resistance and durability.

[0019] (2) The present invention introduces modified graphene: silicon-oxygen bonds and surface functional groups such as mercapto and amino groups form covalent bonds or hydrogen bonds with polysilazane, and the sheet structure forms a mechanical interlocking network to enhance the bonding strength; form a "thermal barrier" to delay high-temperature decomposition and inhibit volume shrinkage; fill micro defects, improve density, enhance insulation, and increase breakdown voltage; carbonize at high temperature to form a dense carbon layer, adsorb free radicals, and cooperate with fluorocarbon polymers to enhance the flame retardant effect; enhance hydrophobicity and delay the formation of ice layers; two-dimensional sheets form a "maze effect", improve density, and block electrochemical and chemical corrosion.

[0020] (3) The present invention introduces a telomer: it forms a covalent bond with polysilazane to enhance the interface bonding. After hydrolysis, the siloxane group can form a hydrogen bond or covalent bond with the hydroxyl group on the surface of the substrate, and at the same time cross-links itself to form a network structure, which significantly improves the adhesion; the siloxane skeleton can form a ceramic protective layer at high temperature, and the fluorocarbon segment can reduce the molecular thermal motion and reduce the degradation rate at high temperature. The two can work together to make the coating stable at high temperature; the charge mobility in the siloxane molecular structure is low, and the intermolecular gap is small, which can inhibit electronic transition. The fluorocarbon chain makes the coating structure more compact, reduces pores and defects, and reduces the breakdown probability. The network structure formed after the telomer and polysilazane are cross-linked can evenly disperse the electric field, avoid breakdown caused by local electric field concentration, and further improve the insulation withstand voltage strength; a silicon dioxide carbon layer is formed at high temperature to block oxygen and heat; the fluorocarbon segment reduces surface tension, forms hydrophobic properties, and achieves anti-icing; improves waterproofness, blocks ion penetration, resists chemical corrosion, and protects the substrate.

[0021] (4) The present invention introduces a synergist: polar groups such as hydroxyl and carboxyl groups on the surface form hydrogen bonds or covalent bonds with silicon-oxygen bonds, thereby enhancing the internal cross-linking of the coating. The phosphate groups of phytic acid improve the interfacial bonding strength, and the adhesion is further improved by combining with the grinding treatment; high thermal conductivity and thermal stability avoid local overheating, promote the formation of an expanding carbonized layer, delay heat penetration, inhibit thermal degradation, and improve the upper temperature resistance and thermal aging resistance of the coating; form an "insulating barrier network", increase the length of the charge migration path, and inhibit electron breakdown; reduce pores and defects in the coating, reduce ion mobility, and increase the breakdown voltage; enhance the uniformity of the coating and reduce local electric field concentration; condensed phase In the process, the degradation products of the synergist promote the cross-linking of residual coke, which insulates heat and oxygen; the layered structure is embedded in the carbon layer, enhancing the mechanical strength of the carbon layer and avoiding cracking; in the gas phase, the synergist releases non-flammable gas, and phytic acid produces phosphorus-containing gas, which captures combustion free radicals and inhibits the spread of flames; the synergistic fluorocarbon surfactant reduces the surface energy, fills the pores of the coating, forms a "hydrophobic barrier", forms a super-hydrophobic surface, and delays the condensation of ice; makes the coating denser and isolates the corrosive medium; the phosphate group chelates the metal ions to inhibit electrochemical corrosion; forms an "electronic barrier" to interfere with the conduction of corrosion current; the fluorine groups on the surface are chemically inert and can resist erosion by corrosive media such as acids and alkalis.

[0022] (5) The present invention introduces modified zinc oxide: the long-chain organic group improves the compatibility with the organic matrix, and the nanorod-like structure forms a chemical bond with the matrix to enhance the adhesion; the nanorods can fill the internal pores of the coating and reduce interface defects; the phosphate chelates the iron ions in the rust layer to form a chemical anchor, and mechanically wedges into the pores of the rust layer with the nanorod structure, greatly improving the adhesion of the coating on the rusted matrix; the one-dimensional structure forms a heat conduction network to accelerate heat diffusion and enhance the high-temperature aging resistance; after uniform dispersion, the density and insulation resistance are improved, and the high aspect ratio can also form a "barrier effect" to hinder electron migration, enhance the breakdown voltage resistance of the coating, and enhance the insulation withstand voltage performance; absorb heat at high temperature, catalyze the dehydration of the polymer matrix into carbon, and enhance the flame retardant grade; strong hydrophobicity combined with fluorocarbon surfactants and fluorocarbon segments can reduce moisture adsorption and penetration, and can also hinder the penetration of corrosive media, play a cathodic protection role, and enhance the anti-corrosion life.

[0023] (6) The present invention introduces a small amount of multi-walled carbon nanotubes: forming a three-dimensional network structure in the coating to improve the cohesion of the coating; the graphitized structure acts as a "thermal skeleton" to inhibit the thermal decomposition of the polysilazane matrix at high temperature and delay aging; constructing an efficient thermal conductive network in the coating to avoid cracking or insulation failure of the coating caused by uneven temperature; it can act as a "charge trap" to inhibit carrier migration and optimize insulation performance; the one-dimensional nanostructure can form a multi-level rough surface together with modified silica, etc., and combined with fluorocarbon surfactants and fluorocarbon segments, it can significantly improve the hydrophobic angle of the coating and reduce ice condensation; it can extend the penetration path of the corrosive medium, and the high strength and flexibility can improve wear resistance and impact resistance.

[0024] Therefore, the polysilazane-graphene composite insulating and voltage-resistant protective coating for electric power equipment prepared by the present invention has excellent rust surface adhesion, high temperature resistance, insulation and voltage resistance, flame retardancy, waterproof and anti-icing ability, and corrosion resistance, as well as a broader application prospect. DETAILED DESCRIPTION

[0025] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0026] Unless otherwise specified, some of the raw materials used in the following examples and comparative examples of the present invention are as follows: Polysilazane was purchased from Anhui Aiyota Silicone Oil Co., Ltd.; fluorocarbon surfactant (Zonyl FSN 100) was purchased from Shenzhen Baileding Biological Co., Ltd.

[0027] Example 1: A method for preparing a polysilazane-graphene composite insulating and voltage-resistant protective coating for power equipment is as follows: S1: 5 g of hydrophobic silica nanoparticles were added to 100 mL of toluene and ultrasonically dispersed for 30 min. Then, 1 mL of triethylamine was added and stirred under nitrogen for 20 min. 20 mL of a 0.01 mol / L toluene solution of heptafluorodecyltrichlorosilane was added and stirred for 18 h. After centrifugation, the precipitate was washed three times with dilute hydrochloric acid, deionized water, anhydrous ethanol, and toluene, respectively, and dried in vacuo at 50 °C for 3 h to obtain modified silica. S2: 5 g of graphene oxide was added to 100 mL of deionized water and ultrasonically treated for 30 min. The pH was then adjusted to 8 with 25% ammonia water. 0.2 g of silane coupling agent KH580 was then added and stirred at 40°C for 12 h. After centrifugation, the precipitate was washed 3-5 times with anhydrous ethanol and finally dried in vacuum at 85°C for 6 h to obtain modified graphene. S3: Under an argon atmosphere at 0°C, 5.2 g of methylamineethanol was added dropwise to 16 g of acryloyloxytriisopropylsilane while stirring. After stirring for 2 h, 105 mL of tetrahydrofuran and 7.8 g of triethylamine were added dropwise at 0°C. 7 g of acryloyl chloride was added dropwise. After reacting for 6 h, the mixture was filtered and the filtrate was evaporated to remove tetrahydrofuran. 35 mL of ethyl acetate was then added and stirred for 30 min. Finally, the mixture was extracted with a saturated sodium chloride solution and the ethyl acetate layer was dried over sodium sulfate. The mixture was filtered and concentrated to obtain a prepolymer. S4: 4.5 g of dodecafluoroheptyl methacrylate, 4 g of prepolymer, 0.4 g of silane coupling agent KH580, 0.045 g of azobisisobutyronitrile, and 12 mL of tetrahydrofuran were mixed and stirred at 65°C under a nitrogen atmosphere for 24 h. The mixture was then poured into 80 mL of -30°C hexane and stirred for 10 min. The mixture was filtered and dried under vacuum at 23°C for 12 h to obtain a telomer. S5: Add 10 g of lithium fluoride to 200 mL of 9 mol / L hydrochloric acid aqueous solution and stir for 20 min. Then add 10 g of titanium aluminum carbide and stir for 45 h. After centrifugation, wash the precipitate with deionized water 5 times and finally dry it in vacuum at 55 °C for 12 h to obtain pretreated nanosheets. S6: Adjust the pH of 190 mL of 50% phytic acid aqueous solution to 7 with 25% ammonia water, then add 10 g of pretreated nanosheets and grind for 12 h. Then, rotary evaporate to 40 mL at 85 °C to obtain the synergist. S7: 0.8 g of octadecyl phosphate was added to 80 mL of toluene and stirred at 55°C for 30 min. Then, 1.6 g of zinc oxide nanorods was added and stirred at 1000 rpm for 12 h under a nitrogen atmosphere at 55°C. After cooling to 20°C, the mixture was centrifuged and washed with anhydrous ethanol and toluene three times each, and then dried in vacuum at 55°C for 6 h to obtain modified zinc oxide. S8: Add 4 g of modified silica, 4 g of modified graphene, 1.5 g of multi-walled carbon nanotubes, 0.5 g of modified zinc oxide, and 1 g of a fluorocarbon surfactant to 130 g of tetrahydrofuran, and perform ultrasonic dispersion at a power of 600 W at 5° C. for 60 min. Filter through a filter membrane with a pore size of 0.8 μm to obtain a mixed dispersion; S9: Add 30 g of polysilazane and 3 g of the telomer to 141 g of the mixed dispersion and stir for 1 hour. Then add 1 g of the synergist and stir at 1000 r / min for 30 minutes to obtain a polysilazane-graphene composite insulating voltage-resistant protective coating for power equipment.

[0028] Example 2: A method for preparing a polysilazane-graphene composite insulating voltage-resistant protective coating for power equipment is as follows: S1: 5.5 g of hydrophobic silica nanoparticles were added to 110 mL of toluene and ultrasonically dispersed for 45 min. 1.1 mL of triethylamine was then added and stirred under a nitrogen atmosphere for 25 min. 22 mL of a 0.01 mol / L toluene solution of heptafluorodecyltrichlorosilane was added and stirred for 19 h. After centrifugation, the precipitate was washed four times with dilute hydrochloric acid, deionized water, anhydrous ethanol, and toluene, respectively, and dried in vacuo at 55°C for 4 h to obtain modified silica. S2: 7.5 g of graphene oxide was added to 110 mL of deionized water and ultrasonically treated for 45 min. The pH was then adjusted to 8.5 with 25% ammonia water. 0.3 g of silane coupling agent KH580 was then added and stirred at 43°C for 14 h. After centrifugation, the precipitate was washed four times with anhydrous ethanol and finally dried in vacuum at 88°C for 9 h to obtain modified graphene. S3: Under an argon atmosphere at 1°C, 6.4 g of methylamineethanol was added dropwise to 19.4 g of acryloyloxytriisopropylsilane while stirring. After stirring for 2.5 h, 127.5 mL of tetrahydrofuran and 9.5 g of triethylamine were added dropwise at 1°C, and 8.5 g of acryloyl chloride was added dropwise. After reacting for 7 h, the mixture was filtered and the filtrate was evaporated to remove tetrahydrofuran. Then, 42.5 mL of ethyl acetate was added and stirred for 45 min. Finally, the mixture was extracted with a saturated sodium chloride solution, and the ethyl acetate layer was dried over sodium sulfate. After filtration and concentration, a prepolymer was obtained. S4: 5 g of dodecafluoroheptyl methacrylate, 4.5 g of prepolymer, 0.45 g of silane coupling agent KH580, 0.05 g of azobisisobutyronitrile, and 13.5 mL of tetrahydrofuran were mixed and stirred at 68°C under a nitrogen atmosphere for 27 h. The mixture was then poured into 90 mL of -25°C hexane and stirred for 15 min. The mixture was filtered and dried under vacuum at 25°C for 16 h to obtain a telomer. S5: 12.5 g of lithium fluoride was added to 250 mL of 9 mol / L hydrochloric acid aqueous solution and stirred for 25 min. Then, 12.5 g of titanium aluminum carbide was added and stirred for 47.5 h. After centrifugation, the precipitate was washed with deionized water 6 times and finally dried in vacuum at 58 °C for 14 h to obtain pretreated nanosheets; S6: Adjust the pH of 215 mL of 55% phytic acid solution to 7 with 25% ammonia water, then add 11.5 g of pretreated nanosheets and grind for 14 h. Then, rotary evaporate to 45 mL at 88 °C to obtain the synergist. S7: 0.9 g of octadecyl phosphate was added to 90 mL of toluene and stirred at 58°C for 45 min. Then, 1.8 g of zinc oxide nanorods was added and stirred at 1100 rpm for 13 h under a nitrogen atmosphere at 58°C. After cooling to 30°C, the mixture was centrifuged and washed with anhydrous ethanol and toluene four times, respectively, and then dried in vacuum at 58°C for 8 h to obtain modified zinc oxide. S8: adding 4.5 g of modified silica, 4.5 g of modified graphene, 1.3 g of multi-walled carbon nanotubes, 1.2 g of modified zinc oxide, and 1.5 g of a fluorocarbon surfactant to 180 g of tetrahydrofuran, and performing ultrasonic dispersion at a power of 600-700 W for 60-90 min at 5-10° C., and filtering through a filter membrane with a pore size of 0.8 μm to obtain a mixed dispersion; S9: Add 40 g of polysilazane and 4 g of telomer to 193 g of the mixed dispersion and stir for 1.5 h. Then add 2 g of synergist and stir at 1300 r / min for 45 min to obtain a polysilazane-graphene composite insulating voltage-resistant protective coating for power equipment.

[0029] Example 3: A method for preparing a polysilazane-graphene composite insulating voltage-resistant protective coating for power equipment is as follows: S1: 6 g of hydrophobic silica nanoparticles were added to 120 mL of toluene and ultrasonically dispersed for 60 min. 1.2 mL of triethylamine was then added and stirred under a nitrogen atmosphere for 30 min. 24 mL of a 0.01 mol / L toluene solution of heptafluorodecyltrichlorosilane was added and stirred for 20 h. After centrifugation, the precipitate was washed with dilute hydrochloric acid, deionized water, anhydrous ethanol, and toluene five times each, and then dried in vacuo at 60 °C for 5 h to obtain modified silica. S2: 10 g of graphene oxide was added to 120 mL of deionized water and ultrasonically treated for 60 min. The pH was then adjusted to 9 with 25% ammonia water. 0.4 g of silane coupling agent KH580 was then added and stirred at 45°C for 15 h. After centrifugation, the precipitate was washed five times with anhydrous ethanol and finally dried in vacuum at 90°C for 12 h to obtain modified graphene. S3: Under an argon atmosphere at 2°C, 7.5 g of methylamineethanol was added dropwise to 22.8 g of acryloyloxytriisopropylsilane while stirring. After stirring for 3 h, 150 mL of tetrahydrofuran and 11.1 g of triethylamine were added at 2°C, and 10 g of acryloyl chloride was added dropwise. After reacting for 8 h, the mixture was filtered and the filtrate was evaporated to remove tetrahydrofuran. Then, 50 mL of ethyl acetate was added and stirred for 60 min. Finally, the mixture was extracted with a saturated sodium chloride solution, and the ethyl acetate layer was dried over sodium sulfate. After filtration and concentration, a prepolymer was obtained. S4: 5.6 g of dodecafluoroheptyl methacrylate, 5 g of prepolymer, 0.5 g of silane coupling agent KH580, 0.056 g of azobisisobutyronitrile, and 15 mL of tetrahydrofuran were mixed and stirred at 70°C under a nitrogen atmosphere for 30 h. The mixture was then poured into 100 mL of -20°C hexane and stirred for 20 min. The mixture was filtered and dried under vacuum at 27°C for 20 h to obtain a telomer. S5: 15 g of lithium fluoride was added to 300 mL of 9 mol / L hydrochloric acid aqueous solution and stirred for 30 min. Then, 15 g of titanium aluminum carbide was added and stirred for 50 h. After centrifugation, the precipitate was washed with deionized water 7 times and finally dried in vacuum at 60 °C for 15 h to obtain pretreated nanosheets. S6: Adjust the pH of 240 mL of 60% phytic acid aqueous solution to 7 with 25% ammonia water, then add 13 g of pretreated nanosheets and grind for 15 h. Then, rotary evaporate to 50 mL at 90 °C to obtain the synergist. S7: 1 g of octadecyl phosphate was added to 100 mL of toluene and stirred at 60°C for 60 min. Then, 2 g of zinc oxide nanorods were added and stirred at 1200 rpm for 15 h at 60°C under a nitrogen atmosphere. After cooling to 40°C, the mixture was centrifuged and washed with anhydrous ethanol and toluene five times, respectively, and then dried in vacuum at 60°C for 10 h to obtain modified zinc oxide. S8: Add 5 g of modified silica, 5 g of modified graphene, 2 g of multi-walled carbon nanotubes, 2 g of modified zinc oxide, and 2 g of a fluorocarbon surfactant to 230 g of tetrahydrofuran, and perform ultrasonic dispersion at a power of 700 W at 10° C. for 90 min. Filter through a filter membrane with a pore size of 0.8 μm to obtain a mixed dispersion; S9: Add 50 g of polysilazane and 5 g of telomer to 246 g of the mixed dispersion and stir for 2 h. Then add 3 g of synergist and stir at 1500 r / min for 60 min to obtain a polysilazane-graphene composite insulating voltage-resistant protective coating for power equipment.

[0030] Comparative Example 1: Compared with Example 1, this comparative example only does not add "modified silicon dioxide" during the preparation process of S8. The remaining steps and parameters are the same, and this comparative example will not be repeated. Finally, a polysilazane-graphene composite insulating voltage-resistant protective coating for power equipment is obtained.

[0031] Comparative Example 2: Compared with Example 1, this comparative example only does not add "modified graphene" during the preparation process of S8. The remaining steps and parameters are the same, and this comparative example will not be repeated. Finally, a polysilazane-graphene composite insulating voltage-resistant protective coating for power equipment is obtained.

[0032] Comparative Example 3: Compared with Example 1, this comparative example only replaces the "telomer" added during the preparation of S9 with the "prepolymer" prepared by S3. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a polysilazane-graphene composite insulating and voltage-resistant protective coating for power equipment is obtained.

[0033] Comparative Example 4: Compared with Example 1, this comparative example only does not add "polymer" during the preparation of S9. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a polysilazane-graphene composite insulating and voltage-resistant protective coating for power equipment is obtained.

[0034] Comparative Example 5: Compared with Example 1, this comparative example only replaces the "synergist" added during the preparation of S8 with the "pretreated nanosheets" prepared by S5. The remaining steps and parameters are the same, and this comparative example will not be repeated. Finally, a polysilazane-graphene composite insulating voltage-resistant protective coating for power equipment is obtained.

[0035] Comparative Example 6: Compared with Example 1, this comparative example only does not add "modified zinc oxide" during the preparation process of S8. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a polysilazane-graphene composite insulating and voltage-resistant protective coating for power equipment is obtained.

[0036] Comparative Example 7: Compared with Example 1, this comparative example only does not add "multi-walled carbon nanotubes" during the preparation of S8. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a polysilazane-graphene composite insulating and voltage-resistant protective coating for power equipment is obtained.

[0037] Comparative Example 8: Compared with Example 1, this comparative example only does not add "thermal insulation microcapsules" during the preparation of S8. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a polysilazane-graphene composite insulating and voltage-resistant protective coating for power equipment is obtained.

[0038] Performance testing: The polysilazane-graphene composite insulating and pressure-resistant protective coatings for power equipment prepared in Examples 1 to 3 of the present invention and Comparative Examples 1 to 8 were uniformly sprayed onto the surfaces of a constant-temperature aluminum plate, a ceramic plate, and a rusted iron plate (surface dust and a peelable rust layer were polished off) at 130° C. to form a 0.5 mm thick coating, which was then cured for 6 hours to obtain test pieces. Determination of adhesion: With reference to the GB / T9286-2021 "Paint and Varnish Cross-Cut Test" standard, the coating adhesion grades of the test pieces made of the polysilazane-graphene composite power equipment insulating voltage-resistant protective coatings prepared in Examples 1 to 3 of the present invention and Comparative Examples 1 to 8 were measured (graded from 0 to 5, with grade 0 being the strongest and grade 5 being the worst). The test results are shown in Table 1. Determination of high temperature resistance: With reference to GB / T 1735-2009 "Determination of Heat Resistance of Paints and Varnishes", the adhesion (grade) of aluminum sample coatings of the polysilazane-graphene composite insulating voltage-resistant protective coatings for power equipment prepared in Examples 1 to 3 and Comparative Examples 1 to 8 of the present invention after exposure to 300°C for 5000 hours was measured. The measurement results are shown in Table 1. Determination of breakdown voltage: With reference to QJ 2220.3-1992 "Test method for electrical insulation performance of coatings - Measurement method for breakdown voltage, breakdown strength and withstand voltage at power frequency", the breakdown voltage (kV·mm) of the aluminum sample coatings made of the polysilazane-graphene composite power equipment insulation withstand voltage protective coatings prepared in Examples 1 to 3 and Comparative Examples 1 to 8 of the present invention was measured. -1 ), the test results are shown in Table 1.

[0039] Table 1: Performance test results of Examples 1-3 and Comparative Examples 1-8 Determination of flame retardancy: With reference to GB / T 2406.2-2009 "Determination of Combustion Behavior of Plastics by Oxygen Index Method - Part 2: Room Temperature Test", the limiting oxygen index (%) of aluminum sample coatings made from the polysilazane-graphene composite insulating and voltage-resistant protective coatings for power equipment prepared in Examples 1 to 3 and Comparative Examples 1 to 8 of the present invention was measured. The test results are shown in Table 2. Determination of water contact angle: Referring to the measurement standard GB / T 24368-2009 "Determination of contact angles of paint and varnish films", the water contact angles (°) of aluminum sample coatings made from the polysilazane-graphene composite insulating and voltage-resistant protective coatings for power equipment prepared in Examples 1 to 3 and Comparative Examples 1 to 8 of the present invention were measured. The test results are shown in Table 2. Determination of corrosion resistance: Referring to the test standard of GB / T10125-2021 "Artificial Atmosphere Corrosion Test-Salt Spray Test", the aluminum specimens were edge-sealed with epoxy putty and then placed in a salt spray test chamber. At 35°C, pH = 7, 5% sodium chloride solution was subjected to a 24-hour salt spray and 24-hour drying cycle test. Samples were taken and observed every 48 hours, and the test duration of pitting and bubbling on the surface of each specimen was recorded. The neutral salt spray test was terminated when pitting and bubbling appeared on the last specimen. The corrosion resistance (h) of the aluminum specimens made of the polysilazane-graphene composite power equipment insulating pressure-resistant protective coatings prepared in Examples 1-3 and Comparative Examples 1-8 of the present invention was determined according to the above method. The test results are shown in Table 2.

[0040] Table 2: Performance test results of Examples 1-3 and Comparative Examples 1-8

[0041] Data Analysis: It can be seen from Table 1 and Table 2 that the polysilazane-graphene composite insulating and voltage-resistant protective coating for electric power equipment prepared in the embodiment of the present invention has excellent adhesion, high temperature resistance, insulating and voltage-resistant capability, flame retardancy, water resistance, anti-icing property, and corrosion resistance.

[0042] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A polysilazane-graphene composite insulating voltage-resistant protective coating for power equipment, characterized in that: The invention comprises the following raw materials in parts by weight: 30-50 parts of polysilazane, 3-5 parts of telomer, 1-3 parts of synergist, 4-5 parts of modified silicon dioxide, 4-5 parts of modified graphene, 1.5-2 parts of multi-walled carbon nanotubes, 0.5-2 parts of modified zinc oxide, 1-2 parts of fluorocarbon surfactant and 130-230 parts of tetrahydrofuran.

2. The polysilazane-graphene composite insulating voltage-resistant protective coating for electric power equipment according to claim 1, characterized in that: The preparation method of the telomer is as follows: A1: Under an argon atmosphere at 0-2°C, methylamineethanol was added dropwise to acryloyloxytriisopropylsilane with stirring. After stirring for 2-3 hours, tetrahydrofuran, triethylamine, and acryloyl chloride were added dropwise. After reacting for 6-8 hours, the mixture was filtered and the filtrate was rotary evaporated to remove tetrahydrofuran. Ethyl acetate was then added and stirred for 30-60 minutes. Finally, the mixture was extracted with a saturated sodium chloride solution, and the ethyl acetate layer was dried over sodium sulfate. The mixture was filtered and concentrated to obtain a prepolymer. A2: Mix dodecafluoroheptyl methacrylate, prepolymer, silane coupling agent KH580, azobisisobutyronitrile, and tetrahydrofuran, stir under a nitrogen atmosphere at 65-70°C for 24-30 hours, then pour into hexane at -30-20°C, stir for 10-20 minutes, filter, and vacuum dry to obtain a telomer.

3. The polysilazane-graphene composite insulating voltage-resistant protective coating for electric power equipment according to claim 2, characterized in that: The usage ratio of acryloyloxytriisopropylsilane, methylamineethanol, tetrahydrofuran, triethylamine, acryloyl chloride, and ethyl acetate in A1 is 16-22.8 g: 5.2-7.5 g: 105-150 mL: 7.8-11.1 g: 7-10 g: 35-50 mL; The usage ratio of dodecafluoroheptyl methacrylate, prepolymer, silane coupling agent KH580, azobisisobutyronitrile, tetrahydrofuran, and hexane in A2 is 4.5-5.6 g: 4-5 g: 0.4-0.5 g: 0.045-0.056 g: 12-15 mL: 80-100 mL.

4. The polysilazane-graphene composite insulating voltage-resistant protective coating for electric power equipment according to claim 1, characterized in that: The preparation method of the synergist is as follows: B1: adding lithium fluoride to a hydrochloric acid aqueous solution and stirring for 20-30 minutes, then adding titanium aluminum carbide and stirring for 45-50 hours, centrifuging, washing the precipitate, and vacuum drying to obtain pretreated nanosheets; B2: After adjusting the pH of the phytic acid aqueous solution to 7, the pretreated nanosheets were added and ground for 12-15 hours, and the synergist was obtained after rotary evaporation.

5. The polysilazane-graphene composite insulating voltage-resistant protective coating for electric power equipment according to claim 4, characterized in that: The ratio of the hydrochloric acid aqueous solution, lithium fluoride, and titanium aluminum carbide in B1 is 200-300 mL: 10-15 g: 10-15 g; The concentration of the hydrochloric acid aqueous solution in B1 is 9 mol / L; The ratio of the phytic acid aqueous solution and the pretreated nanosheets in B2 is 190-240 mL: 10-13 g; The mass fraction of the phytic acid aqueous solution in B2 is 50%-60%.

6. The polysilazane-graphene composite insulating voltage-resistant protective coating for electric power equipment according to claim 1, characterized in that: The preparation method of the modified silicon dioxide is as follows: Add hydrophobic silica nanoparticles to toluene and perform ultrasonic dispersion for 30-60 minutes, then add triethylamine and stir under a nitrogen atmosphere for 20-30 minutes, add a toluene solution of heptafluorodecyltrichlorosilane and stir for 18-20 hours, centrifuge, wash the precipitate, and vacuum dry to obtain modified silica; The usage ratio of toluene, hydrophobic silica nanoparticles, triethylamine, and toluene solution of heptadecafluorodecyltrichlorosilane is 100-120 mL: 5-6 g: 1-1.2 mL: 20-24 mL; The concentration of the toluene solution of heptafluorodecyltrichlorosilane is 0.01 mol / L.

7. The polysilazane-graphene composite insulating voltage-resistant protective coating for electric power equipment according to claim 1, characterized in that: The preparation method of the modified graphene is as follows: Graphene oxide is added to deionized water and ultrasonically treated for 30-60 minutes, after which the pH is adjusted to 8-9, and then a silane coupling agent KH580 is added and stirred at 40-45° C. for 12-15 hours. After centrifugation, the mixture is washed and vacuum-dried to obtain modified graphene; The mass ratio of the deionized water, graphene oxide, and silane coupling agent KH580 is 100-120:5-10:0.2-0.

4.

8. The polysilazane-graphene composite insulating voltage-resistant protective coating for electric power equipment according to claim 1, characterized in that: The preparation method of the modified zinc oxide is as follows: Add octadecyl phosphate to toluene and stir at 55-60° C. for 30-60 minutes, then add zinc oxide nanorods and stir at 55-60° C. in a nitrogen atmosphere for 12-15 hours. After cooling, centrifuge and wash the precipitate, vacuum dry to obtain modified zinc oxide.

9. The polysilazane-graphene composite insulating voltage-resistant protective coating for electric power equipment according to claim 8, characterized in that: The usage ratio of toluene, octadecyl phosphate and zinc oxide nanorods is 80-100 mL: 0.8-1 g: 1.6-2 g.

10. A method for preparing the polysilazane-graphene composite insulating and voltage-resistant protective coating for power equipment according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: adding modified silica, modified graphene, multi-walled carbon nanotubes, modified zinc oxide, and a fluorocarbon surfactant to tetrahydrofuran and performing ultrasonic dispersion at 5-10° C. for 60-90 min, and filtering to obtain a mixed dispersion; S2: Add polysilazane and telomer to the mixed dispersion and stir for 1-2 hours, then add synergist and stir evenly to obtain a polysilazane-graphene composite insulating voltage-resistant protective coating for power equipment.

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