Graphene modified polysilazane composite coating for electric power protection and preparation method of graphene modified polysilazane composite coating

Abstract

The invention discloses a graphene modified polysilazane composite coating for electric power protection and a preparation method of the graphene modified polysilazane composite coating, and relates to the technical field of protective coatings. The graphene modified polysilazane composite coating for electric power protection at least comprises the following raw materials in parts by mass: 30-40 parts of perhydropolysilazane resin; 8 to 15 parts of phosphorus-containing polysilazane resin; 1 to 5 parts of aminated graphene; 1-5 parts of fluorine-containing silane coupling agent modified nano silicon dioxide; 3-10 parts of a synergistic flame retardant; 0.2 to 0.8 part of a silane coupling agent; 0.1 to 0.5 part of a catalyst; 0.1 to 0.3 part of a defoaming agent; 0.1 to 0.5 part of fumed silica; 5-15 parts of pigment and filler; and 30-40 parts of a xylene / n-butyl alcohol mixed solvent. The graphene modified polysilazane composite coating prepared by the invention has efficient flame retardance, super-hydrophobicity and long-acting corrosion resistance, and can be directly sprayed under the conditions of temperature, rust and electrification.

Description

Technical Field

[0001] This invention relates to the field of protective coating technology, specifically to graphene-modified polysilazane composite coatings for power protection and their preparation methods. Background Technology

[0002] Power transmission and distribution equipment, such as transformer casings, switchgear, busbar trunking, and cable trays, are exposed to outdoor or complex industrial environments for extended periods, enduring ultraviolet radiation, temperature cycling, humidity condensation, salt spray corrosion, chemical contaminants, and the risk of fire caused by accidental electric arcs or overheating. Therefore, applying a long-lasting protective coating to their surfaces is a crucial measure to ensure the safe and stable operation of the power grid.

[0003] Currently, commonly used electrical protective coatings include epoxy resin coatings, zinc-rich coatings, and silicone resin coatings. Epoxy resin coatings have strong adhesion and good chemical resistance, but poor weather resistance, high brittleness, and are prone to decomposition at high temperatures (>100℃), failing to meet the protection requirements of energized and heated equipment. Zinc-rich coatings offer good sacrificial anode protection, but require extremely high-quality surface preparation for application, cannot be applied to rusted surfaces, and have poor insulation properties. Traditional silicone resin coatings offer high temperature resistance and good insulation, but typically have high curing temperatures and long curing cycles, generally average adhesion, and limited flame retardant properties, mostly physical flame retardancy, making it difficult to meet high-standard flame retardant requirements.

[0004] Polysilazane, as a new generation of inorganic-organic hybrid polymer precursors, can be hydrolyzed and cross-linked to form films at room temperature and can gradually transform into ceramics at higher temperatures. It combines the ease of application of polymer coatings with the high-temperature resistance, high hardness, and oxidation resistance of ceramic materials, showing great potential in the field of power protection. However, pure polysilazane coatings have high hardness but insufficient toughness, making them prone to microcracks and detachment under temperature cycling or mechanical impact. Their flame retardancy mainly stems from the physical isolation provided by the formation of a silica ceramic layer at high temperatures, lacking an efficient gas-phase or condensed-phase flame retardant mechanism, resulting in insufficient suppression of early-stage flames. Furthermore, their long-term shielding ability against water vapor and corrosive media is limited, and their surface energy control range is narrow, making it difficult to achieve special surface functions such as superhydrophobicity. While there have been attempts to combine polysilazane with various fillers in existing technologies, simple physical blending easily leads to uneven filler dispersion and weak interfacial bonding, resulting in limited performance improvement and potential negative impacts. Therefore, existing polysilazane coatings suffer from poor flame retardancy, insufficient protective performance, and easy detachment, severely limiting the application of this technology. Summary of the Invention

[0005] The purpose of this invention is to provide a graphene-modified polysilazane composite coating for power protection and its preparation method, thereby solving the following technical problems: Existing polysilazane composite coatings used for power protection suffer from insufficient flame retardancy, inadequate protective performance, and easy peeling.

[0006] The objective of this invention can be achieved through the following technical solutions: A graphene-modified polysilazane composite coating for electrical protection comprises at least the following raw materials by weight: 30-40 parts of all-hydrogen polysilazane resin; 8-15 parts of phosphorus-containing polysilazane resin; 1-5 parts of amino-based graphene; 1-5 parts of fluorinated silane coupling agent-modified nano-silica; 3-10 parts of synergistic flame retardant; 0.2-0.8 parts of silane coupling agent; 0.1-0.5 parts of catalyst; 0.1-0.3 parts of defoamer; 0.1-0.5 parts of fumed silica; 5-15 parts of pigments and fillers; 30-40 parts of xylene / n-butanol mixed solvent.

[0007] As a further aspect of the present invention, the preparation method of the phosphorus-containing polysilazane resin includes at least the following preparation steps: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and vinyl-containing polysilazane were dissolved in toluene, and a mixed solution of azobisisobutyronitrile and toluene was added dropwise. After reflux reaction, the mixture was distilled under reduced pressure, washed, rotary evaporated and dried to obtain phosphorus-containing polysilazane resin.

[0008] As a further aspect of the present invention: the mass ratio of the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to the vinyl-containing polysilazane is 2-5:10.

[0009] As a further aspect of the present invention: the preparation method of the fluorinated silane coupling agent modified nano-silica includes at least the following steps: Under nitrogen protection, tetrahydrofuran, trimethoxysilane and 2-(perfluorohexyl)ethyl methacrylate were stirred and mixed, and Karstedt catalyst was added to react. After rotary evaporation, fluorine-modified trimethoxysilane was obtained. Nano-silica was dispersed in anhydrous ethanol, and the fluorinated modified trimethoxysilane was added dropwise to react. After washing and drying, fluorinated silane coupling agent modified nano-silica was obtained.

[0010] As a further aspect of the present invention: the mass ratio of the trimethoxysilane to the 2-(perfluorohexyl)ethyl methacrylate is 1:1-2, and the mass ratio of the nano-silica to the fluorinated modified trimethoxysilane is 10:1-3.

[0011] As a further aspect of the present invention: the volume ratio of xylene to n-butanol in the xylene / n-butanol mixed solvent is 3-5:1; the synergistic flame retardant is at least one of aluminum hypophosphite, ammonium polyphosphate, or melamine polyphosphate; and the silane coupling agent is at least one of γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, or vinyltrimethoxysilane.

[0012] As a further aspect of the present invention: the catalyst is at least one of dibutyltin dilaurate, stannous octoate, or tetraisopropyl titanate; the defoamer is at least one of polyether-modified silicone defoamer or defoaming polymer type defoamer; and the pigment and filler are at least one of mica powder, sericite, barium sulfate, or talc powder.

[0013] The preparation method of the graphene-modified polysilazane composite coating for power protection as described in any of the above methods includes at least the following preparation steps: The perhydropolysilazane resin, phosphorus-containing polysilazane resin, aminated graphene, fluorinated silane coupling agent modified nano-silica, synergistic flame retardant, silane coupling agent, catalyst, defoamer, fumed silica, pigments and fillers, and xylene / n-butanol mixed solvent are mixed and pre-dispersed at 600-1000 r / min for 30-60 min. After grinding to a fineness of ≤20μm, the mixture is filtered to obtain a graphene-modified polysilazane composite coating for power protection.

[0014] The beneficial effects of this invention are: The graphene-modified polysilazane composite coating for power protection provided by this invention uses all-hydrogen polysilazane resin as a high-temperature resistant insulating skeleton, introduces phosphorus-containing polysilazane resin to achieve intrinsic high-efficiency flame retardancy, and adds synergistic flame retardants to significantly improve the flame retardancy rating. A long-lasting corrosion barrier is constructed through aminated graphene, and the amount of aminated graphene added is strictly controlled to ensure high insulation resistance of the coating while achieving excellent anti-corrosion performance. Pigments and fillers are also added to further enhance physical shielding and insulation. Furthermore, fluorinated silane coupling agents are used to modify nano-silica, giving the coating superhydrophobic properties and strong interfacial bonding. This invention also adds silane coupling agents, catalysts, defoamers, fumed silica, pigments, fillers, and other additives to ensure excellent workability and the final coating's density and adhesion on heated (≥100℃) and rusted substrates. This coating is particularly suitable for protecting substation equipment, busbars, cable joints, transformer casings, and other structures that require long-term resistance to high temperatures, humidity, dirt, salt spray, and fire risks. It enables uninterrupted maintenance and greatly ensures the safety and lifespan of the power grid.

[0015] The phosphorus-containing polysilazane resin prepared in this invention chemically bonds a highly efficient 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide flame-retardant structure to the polysilazane molecular chain, achieving uniform molecular-level dispersion of the flame-retardant components. During heating or combustion, phosphorus catalyzes the polysilazane to form a faster and denser cross-linked char layer rich in phosphorus, silicon, oxygen, and nitrogen. This char layer exhibits high strength and good thermal stability, effectively isolating oxygen and heat, inhibiting the generation of combustible gases, and demonstrating a significant phosphorus-silicon synergistic flame-retardant effect, effectively protecting the substrate. This invention combines all-hydrogen polysilazane resin and phosphorus-containing polysilazane resin. The all-hydrogen resin provides higher ceramicization yield and thermal stability, while the introduction of the phosphorus-containing polysilazane resin, on the one hand, improves the brittleness of the pure polysilazane coating through its flexible segments, and on the other hand, acts as a flame-retardant catalyst, triggering and strengthening the char formation process of the entire resin system in the early stages of a fire, achieving both flame-retardant and temperature-resistant enhancement effects.

[0016] This invention also prepared fluorinated silane coupling agent-modified nano-silica. The fluorinated long chains grafted onto the surface of the nano-silica endow the filler with extremely low surface energy, allowing it to accumulate on the coating surface after uniform dispersion, greatly reducing the surface energy of the coating and giving it excellent superhydrophobic properties, making it difficult for water to wet and adhere. Furthermore, the nanosheet structure of aminated graphene is arranged parallel to the substrate in the coating, forming a complex physical barrier network with the modified nano-silica, which greatly extends the penetration path of corrosive media and provides an excellent "maze effect" barrier. Moreover, the silane coupling agent on the surface of the modified nano-silica can form strong chemical bonds with the polysilazane resin and the substrate surface, not only enhancing the interfacial bonding between the filler and the resin and preventing nanoparticle aggregation, but also improving the wetting penetration and adhesion of the coating to rusty substrates. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1: The preparation method of phosphorus-containing polysilazane resin includes the following steps: Under nitrogen protection, 6.48 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 20 mL of toluene were added to a three-necked flask. The temperature was controlled at 80 °C, and the mixture was stirred to dissolve the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. 20 g of vinyl-containing polysilazane (IOTA 9108) was dissolved in 20 mL of toluene and added to the three-necked flask through a constant pressure dropping funnel. The mixture was stirred and stirred until homogeneous. Then, a mixed solution of 0.2 g of azobisisobutyronitrile and 20 mL of toluene was added dropwise. After the addition was complete, the mixture was refluxed for 16 h. After the reaction was completed, the toluene was removed by vacuum distillation at 110 °C. The mixture was then washed with tetrahydrofuran and n-hexane, and the solvent was removed by rotary evaporation. Finally, the mixture was dried in a vacuum oven at 80 °C for 5 h to obtain the phosphorus-containing polysilazane resin.

[0019] Example 2: The preparation method of nano-silica modified with fluorinated silane coupling agent includes the following steps: Under nitrogen protection, 40 mL of tetrahydrofuran, 10 g of trimethoxysilane (CG-58) and 17.5 g of 2-(perfluorohexyl)ethyl methacrylate (TEMAc-6) were stirred at 600 r / min until homogeneous. 0.0175 g of Karstedt catalyst was added and stirred. The reaction was carried out at 80 °C for 48 h. Heating was stopped to terminate the reaction. The solvent in the reaction system was removed by rotary evaporation to obtain fluorinated modified trimethoxysilane. 10g of nano-silica was added to anhydrous ethanol and sonicated for 30min. 2g of the above-mentioned fluorine-modified trimethoxysilane was added dropwise. After the addition was completed, the flask was immersed in a constant temperature water bath at 45℃ and reacted for 12h under magnetic stirring. After centrifugation, the supernatant was discarded and dispersed again in ethanol solution and separated by centrifugation again. The entire washing process was repeated 3 times. The nano-silica was dried in an oven at 90℃ to obtain fluorine-containing silane coupling agent modified nano-silica.

[0020] Example 3: The preparation method of aminated graphene includes the following steps: Under water bath cooling, 100g of graphene oxide was added to 1000mL of 30% concentrated hydrochloric acid and ultrasonically dispersed at 30kHz for 30min. Then, it was stirred at 20℃ for 5h, filtered, and the precipitate was washed with water until neutral. It was then vacuum dried at 60℃ for 10h to obtain purified graphene oxide. Add 80g of the purified graphene oxide to 500mL of 20% hydrogen peroxide aqueous solution, stir and mix well, add 350mL of 6mg / ml amino acid aqueous solution, sonicate at 30kHz for 16min in a water bath, continue stirring and react for 20min, wash and filter with anhydrous ethanol, then wash and filter with distilled water, dry under vacuum at 60℃ for 5h, grind and continue to dry under vacuum at 65℃ for 2h to obtain amino-based graphene.

[0021] Example 4: The preparation method of graphene-modified polysilazane composite coating for power protection includes the following steps: 35 parts by mass of all-hydrogen polysilazane resin (IOTA-PHPS), 10 parts by mass of phosphorus-containing polysilazane resin prepared in Example 1, 2 parts by mass of aminated graphene prepared in Example 3, 2 parts by mass of fluorinated silane coupling agent modified nano-silica prepared in Example 2, 5 parts by mass of ammonium polyphosphate, 0.5 parts by mass of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 0.3 parts by mass of dibutyltin dilaurate, 0.2 parts by mass of polyether-modified organosilicon defoamer, 0.3 parts by mass of fumed silica, 8 parts by mass of mica powder, and 35 parts by mass of xylene / n-butanol (volume ratio 4:1) mixed solvent were mixed and pre-dispersed at 800 r / min for 40 min, ground to a fineness ≤20 μm, and filtered to obtain graphene-modified polysilazane composite coating for power protection.

[0022] Example 5: The preparation method of graphene-modified polysilazane composite coating for power protection includes the following steps: 30 parts by mass of all-hydrogen polysilazane resin (IOTA-PHPS), 15 parts by mass of phosphorus-containing polysilazane resin prepared in Example 1, 4 parts by mass of aminated graphene prepared in Example 3, 4 parts by mass of fluorinated silane coupling agent modified nano-silica prepared in Example 2, 8 parts by mass of ammonium polyphosphate, 0.8 parts by mass of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 0.4 parts by mass of dibutyltin dilaurate, 0.3 parts by mass of polyether-modified organosilicon defoamer, 0.4 parts by mass of fumed silica, 12 parts by mass of mica powder, and 38 parts by mass of xylene / n-butanol (volume ratio 4:1) mixed solvent were mixed and pre-dispersed at 800 r / min for 40 min. The mixture was then ground to a fineness ≤20 μm and filtered to obtain a graphene-modified polysilazane composite coating for power protection.

[0023] Example 6: The preparation method of graphene-modified polysilazane composite coating for power protection includes the following steps: 40 parts by mass of all-hydrogen polysilazane resin (IOTA-PHPS), 8 parts by mass of phosphorus-containing polysilazane resin prepared in Example 1, 1 part by mass of amino-based graphene prepared in Example 3, 1 part by mass of fluorinated silane coupling agent-modified nano-silica prepared in Example 2, 3 parts by mass of ammonium polyphosphate, 0.3 parts by mass of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 0.2 parts by mass of dibutyltin dilaurate, 0.1 parts by mass of polyether-modified organosilicon defoamer, 0.2 parts by mass of fumed silica, 5 parts by mass of mica powder, and 32 parts by mass of xylene / n-butanol (volume ratio 4:1) mixed solvent were mixed and pre-dispersed at 800 r / min for 40 min. The mixture was then ground to a fineness ≤20 μm and filtered to obtain a graphene-modified polysilazane composite coating for power protection.

[0024] Comparative Example 1: The preparation method of silane coupling agent modified nano-silica includes the following steps: Add 10g of nano-silica to anhydrous ethanol and sonicate for 30 minutes. Add 2g of vinyltrimethoxysilane dropwise. After the silane reaction was completed, the flask was immersed in a constant temperature water bath at 45°C and reacted under magnetic stirring for 12 hours. After centrifugation, the supernatant was discarded, and the mixture was dispersed again in an ethanol solution and centrifuged again. The entire washing process was repeated 3 times. The mixture was then dried in a 90°C oven to obtain silane coupling agent modified nano-silica.

[0025] Compared with Example 4, Comparative Example 2 only replaced the phosphorus-containing polysilazane resin prepared in Example 1 with polysilazane (8804R) in Example 4 by the same mass. The other components and preparation methods were completely the same as those in Example 4.

[0026] Compared with Example 4, Comparative Example 3 only replaced the perhydropolysilazane resin added in Example 4 with polysilazane (8804R) by mass, while the other components and preparation methods were completely the same as in Example 4.

[0027] Compared with Example 4, Comparative Example 4 only replaced the fluorinated silane coupling agent modified nano-silica prepared in Example 2 with the silane coupling agent modified nano-silica prepared in Comparative Example 1 by the same mass. The remaining components and preparation methods were completely the same as those in Example 4.

[0028] Compared with Example 4, Comparative Example 5 only did not add the aminated graphene prepared in Example 3, while the other components and preparation methods were completely the same as those in Example 4.

[0029] Compared with Example 4, Comparative Example 6 only did not add the fluorinated silane coupling agent modified nano-silica prepared in Example 2. The other components and preparation methods were completely the same as those in Example 4.

[0030] Performance testing The graphene-modified polysilazane composite coatings prepared in Examples 4-5 and Comparative Examples 2-6 were sprayed using an R51-F type spray gun. The spray gun pressure was set to 0.25 MPa, the flow rate to 40 mL / min, and the spraying distance to approximately 10 cm. The substrate was placed at a 30° angle during spraying. During the spraying process, the spray gun was moved at a uniform speed, and the coating was sprayed alternately from left to right and from top to bottom to ensure a uniform coating thickness. After surface drying at room temperature for 30 minutes, the coating was transferred to a 100°C oven for curing for 2 hours to obtain the polysilazane coating. Subsequently, the coating was conditioned under standard test conditions for 24 hours before performance testing. Adhesion test: The adhesion of the polysilazane coating was tested according to GB / T 9286—1998 "Cross-cut test for paint and varnish films". A cross-cut tester was used to make six horizontal and six vertical cuts on the superhydrophobic coating sample. Then, 3M tape was applied to the entire cut area, and the tape was quickly peeled off at a 60° angle to the coating. The entire peeling time was controlled within 0.5-1 seconds. The test results are shown in Table 1. Contact angle test: The water contact angle (deionized water) was measured using a SZ-CAMC33 contact angle measuring instrument from Shanghai Xuanzhun Instrument Co., Ltd. The test liquid volume was 5 μL, and the average value was taken after 3 measurements. The angle was calculated using either the ellipse method (θ < 90°) or the annular method (θ ≥ 90°). The test results are shown in Table 1. Neutral salt spray test: Following the standard GB / T 10125-2021 "Chemical Atmosphere Corrosion Test - Salt Spray Test" for the preparation and performance study of polysilazane coatings, the coating samples were placed in a salt spray test chamber at 35℃. The salt spray concentration was 5% (mass fraction) NaCl solution, the pH value was 6.5-7.2, and the continuous spraying time was 2000 hours. During the test, the corrosion condition of the coating surface was observed periodically, noting any rust, blistering, or peeling, and the corrosion time and degree were recorded. After the test, the corrosion area ratio of the coating was calculated to evaluate its corrosion resistance. The test results are shown in Table 1. Vertical flammability test (UL-94): The flame retardant properties of the samples were determined using a CZF-2 horizontal and vertical flammability tester manufactured by Jiangning Analytical Instrument Factory, in accordance with ASTM D3801 standard. The sample size was 130mm × 13mm × 3.2mm. The test results are shown in Table 1. Limiting Oxygen Index (LOI) Test: The HC-2C limiting oxygen index tester manufactured by Nanjing Jiangning Analytical Instrument Factory was used to test the oxygen index of the samples according to ASTM D2863-97 standard. The sample size was 130mm × 6.5mm × 3.2mm. The test results are shown in Table 1. Table 1: Statistical Table of Coating Performance Test Data for Examples 4-6 and Comparative Examples 2-6

[0031] As shown in Table 1, the polysilazane coatings prepared by the graphene-modified polysilazane composite coatings for power protection provided in Examples 4-6 of this invention have high flame retardancy, superhydrophobicity, and heavy-duty anti-corrosion properties, and strong adhesion to the substrate, making them difficult to peel off. In Comparative Example 2, replacing the phosphorus-containing polysilazane resin with ordinary polysilazane resulted in a sharp decrease in the flame retardancy of the obtained polysilazane coating. In Comparative Example 3, replacing the all-hydrogen polysilazane resin with ordinary polysilazane resulted in a decrease in the adhesion of the obtained polysilazane coating to level 2 and a deterioration in its anti-corrosion properties. In Comparative Example 4, using a fluorine-free silane coupling agent to modify nano-silica resulted in a decrease in the adhesion of the obtained polysilazane coating, a sharp drop in the contact angle, and a severe deterioration in its salt spray resistance. In Comparative Example 5, without the addition of aminated graphene, the salt spray resistance was the worst. In Comparative Example 6, without the addition of fluorinated siloxane-modified nano-silica, the adhesion of the obtained polysilazane coating decreased, and its waterproof performance was the worst.

[0032] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0033] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A graphene-modified polysilazane composite coating for power protection, characterized in that, It shall include at least the following parts by weight of raw materials: 30-40 parts of all-hydrogen polysilazane resin; 8-15 parts of phosphorus-containing polysilazane resin; 1-5 parts of amino-based graphene; 1-5 parts of fluorinated silane coupling agent-modified nano-silica; 3-10 parts of synergistic flame retardant; 0.2-0.8 parts of silane coupling agent; 0.1-0.5 parts of catalyst; 0.1-0.3 parts of defoamer; 0.1-0.5 parts of fumed silica; 5-15 parts of pigments and fillers; 30-40 parts of xylene / n-butanol mixed solvent.

2. The graphene-modified polysilazane composite coating for power protection according to claim 1, characterized in that, The preparation method of the phosphorus-containing polysilazane resin includes at least the following preparation steps: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and vinyl-containing polysilazane were dissolved in toluene, and a mixed solution of azobisisobutyronitrile and toluene was added dropwise. After reflux reaction, the mixture was distilled under reduced pressure, washed, rotary evaporated and dried to obtain phosphorus-containing polysilazane resin.

3. The graphene-modified polysilazane composite coating for power protection according to claim 2, characterized in that, The mass ratio of the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to the vinyl-containing polysilazane is 2-5:

10.

4. The graphene-modified polysilazane composite coating for power protection according to claim 1, characterized in that, The preparation method of the fluorinated silane coupling agent modified nano-silica includes at least the following steps: Under nitrogen protection, tetrahydrofuran, trimethoxysilane and 2-(perfluorohexyl)ethyl methacrylate were stirred and mixed, and Karstedt catalyst was added to react. After rotary evaporation, fluorine-modified trimethoxysilane was obtained. Nano-silica was dispersed in anhydrous ethanol, and the fluorinated modified trimethoxysilane was added dropwise to react. After washing and drying, fluorinated silane coupling agent modified nano-silica was obtained.

5. The graphene-modified polysilazane composite coating for power protection according to claim 4, characterized in that, The mass ratio of the trimethoxysilane to the 2-(perfluorohexyl)ethyl methacrylate is 1:1-2, and the mass ratio of the nano-silica to the fluorinated modified trimethoxysilane is 10:1-3.

6. The graphene-modified polysilazane composite coating for power protection according to claim 1, characterized in that, The volume ratio of xylene to n-butanol in the xylene / n-butanol mixed solvent is 3-5:

1. The synergistic flame retardant is at least one of aluminum hypophosphite, ammonium polyphosphate, or melamine polyphosphate. The silane coupling agent is at least one of γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, or vinyltrimethoxysilane.

7. The graphene-modified polysilazane composite coating for power protection according to claim 1, characterized in that, The catalyst is at least one of dibutyltin dilaurate, stannous octoate, or tetraisopropyl titanate; the defoamer is at least one of polyether-modified silicone defoamer or defoaming polymer type defoamer; and the pigment and filler are at least one of mica powder, sericite, barium sulfate, or talc powder.

8. The method for preparing graphene-modified polysilazane composite coating for power protection according to any one of claims 1-7, characterized in that, It includes at least the following preparation steps: The perhydropolysilazane resin, phosphorus-containing polysilazane resin, aminated graphene, fluorinated silane coupling agent modified nano-silica, synergistic flame retardant, silane coupling agent, catalyst, defoamer, fumed silica, pigments and fillers, and xylene / n-butanol mixed solvent are mixed and pre-dispersed at 600-1000 r / min for 30-60 min. After grinding to a fineness of ≤20μm, the mixture is filtered to obtain a graphene-modified polysilazane composite coating for power protection.

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