Insulator super-hydrophobic coating based on micro-nano structure design and preparation method and application thereof

Abstract

The invention relates to an insulator super-hydrophobic coating based on micro-nano structure design and a preparation method and application thereof. Comprising the following components in parts by weight: 80 parts of ethanol, 4 parts of a silane coupling agent, 4 parts of deionized water, 4 parts of hydrophobic SiO2 nanoparticles, 18 parts of divinylbenzene, 1000 parts of cyclohexane, 1 part of boron trifluoride diethyl etherate, 2 parts of polydimethylsiloxane, 0.2 part of a polydimethylsiloxane curing agent and 100 parts of ethyl acetate. The problems that an existing insulator RTV coating is insufficient in hydrophobic performance, poor in self-cleaning capacity and high in wet flashover and pollution flashover risk can be solved, and the mechanical strength and the structural stability of the coating are synchronously improved.

Description

Technical Field

[0001] This invention belongs to the field of superhydrophobic coating technology for insulators, and relates to a superhydrophobic coating for insulators, its preparation method and application, especially a superhydrophobic coating for insulators based on micro-nano structure design, its preparation method and application. Background Technology

[0002] Insulators are critical external insulation devices in power systems, and their performance directly affects the reliability and safety of the power grid. In harsh environments such as humidity and pollution, dirt can easily accumulate on the surface of insulators, forming a conductive layer under conditions such as fog, dew, and drizzle. This can cause localized electric arcs to develop into surface flashovers (i.e., "pollution flashover"), resulting in power outages.

[0003] To prevent surface flashover, traditional methods include regular cleaning and applying anti-flashover coatings such as silicone oil / grease. However, these methods suffer from problems such as short maintenance cycles, unstable effectiveness, or environmental pollution. Currently, the commonly used room temperature vulcanizing (RTV) silicone rubber coating for insulators has some hydrophobicity, but it is prone to aging and mechanical wear after long-term outdoor use, and requires regular recoating.

[0004] Superhydrophobic coatings have shown application potential in the field of electrical external insulation due to their excellent self-cleaning, anti-icing, and anti-fouling properties. Superhydrophobic surfaces typically refer to surfaces with a water contact angle greater than 150° and a roll-off angle less than 10°, allowing water droplets to easily roll off and carry away contaminants, thereby keeping the surface clean.

[0005] However, existing superhydrophobic coatings still have the following shortcomings: (1) The wear resistance of the coating is generally insufficient: Under the long-term effects of wind and rain, mechanical friction and other external forces, the coating is prone to physical degradation or chemical wear, resulting in damage to the microstructure and degradation of superhydrophobicity, requiring frequent recoating and significantly increasing maintenance costs. Especially for smooth substrates such as ceramics and glass, the coating adhesion is limited, and local peeling is more likely to occur, further affecting its long-term anti-flashover performance, and it is difficult to improve wear resistance and anti-flashover characteristics in a synergistic way.

[0006] (2) The preparation process is complex and costly: Although laser processing, template method and other methods can construct fine micro-nano structures to achieve superhydrophobic properties, the process is complex and the equipment is expensive, making it difficult to apply on a large scale; the coating preparation and construction requirements are extremely high for equipment and process control, which limits its feasibility for on-site construction on large-size insulating equipment and limits its large-scale promotion and application in the power industry.

[0007] (3) Insufficient electrical insulation performance and adaptability to high-voltage operating conditions of superhydrophobic coatings: Existing superhydrophobic coatings mostly focus on optimizing hydrophobicity and mechanical properties, with insufficient targeted design for synergistic improvement of insulation characteristics and long-term service anti-aging performance under high-voltage electric field environments. The dielectric properties of some composite coatings are inherently limited, which can easily lead to local electric field distortion and micro-discharge phenomena under high-voltage operating conditions, making it difficult to match the stringent electrical safety requirements of insulators under high-voltage and strong electric field environments.

[0008] To address the aforementioned issues, this invention proposes a superhydrophobic coating for insulators based on micro / nano structure design, its preparation method, and its application.

[0009] A search revealed no prior art patents that are identical or similar to this invention. Summary of the Invention

[0010] This invention addresses the shortcomings of existing technologies by proposing a superhydrophobic coating for insulators based on micro-nano structure design, along with its preparation method and application. This invention can solve the problems of insufficient hydrophobicity, poor self-cleaning ability, and high risk of wet flashover and pollution flashover in existing RTV coatings for insulators, while simultaneously improving the mechanical strength and structural stability of the coating.

[0011] The above-mentioned objective of this invention is achieved through the following technical solution: A superhydrophobic coating for insulators based on micro / nano structure design comprises the following components by weight fraction: Ethanol 70-80 parts, silane coupling agent 4-8 parts, deionized water 2.4-4 parts, hydrophobic SiO2 nanoparticles 4-8 parts, divinylbenzene 18-20 parts, cyclohexane 1000-1500 parts, boron trifluoride ethyl ether 1-1.5 parts, polydimethylsiloxane 2-4 parts, polydimethylsiloxane curing agent 0.2-0.4 parts, ethyl acetate 90-100 parts.

[0012] A method for preparing a superhydrophobic coating for insulators based on micro / nano structure design includes the following steps: Step S1: Clean and dry the glass or ceramic sample for pretreatment; Step S2: Mix ethanol, deionized water, and silane coupling agent to prepare a silane coupling agent hydrolysis solution; Step S3: Use a spray gun to spray the hydrolysis solution prepared in step S2 onto the surface of the glass or ceramic sample, and then send the glass or ceramic sample into an oven for curing treatment to obtain a superhydrophobic pre-coating. Step S4: Divinylbenzene is subjected to vacuum distillation to extract high-purity divinylbenzene monomer; Step S5: After thoroughly mixing high-purity divinylbenzene monomer, hydrophobic SiO2 nanoparticles and cyclohexane, boron trifluoride diethyl ether is added to initiate the nanotube synthesis reaction, realizing the directional design and controllable construction of micro and nano structures; after the reaction is completed, the mixture is filtered, and the filter cake is dried under vacuum to obtain composite nanotube particles. Step S6: Mix composite nanotube particles, multi-walled carbon nanotubes, polydimethylsiloxane, polydimethylsiloxane curing agent and ethyl acetate to prepare a superhydrophobic coating; Step S7: Spray the superhydrophobic coating onto the surface of the silanized glass or ceramic sample, and cure it in an oven to obtain a superhydrophobic coating on the surface of the glass or ceramic sample.

[0013] Furthermore, the specific method of step S1 is as follows: Take glass and ceramic samples, rinse them thoroughly with sufficient deionized water to remove surface impurities, and then place them in an ultrasonic cleaning device for surface cleaning; after removal, dry them with nitrogen gas.

[0014] Furthermore, the raw materials for preparing the silane coupling agent hydrolysis solution in step S2 are: silane coupling agent KH550, ethanol and deionized water, with a volume ratio of 1:(0.6~2):(17~18). The solution is stirred at 250~300 rpm for 20~30 minutes on a magnetic stirrer, and then left to stand for 1~2 hours for later use.

[0015] Furthermore, the specific method of step S3 is as follows: Use a gravity spray gun with a nozzle diameter of 1~1.5mm, adjust the spraying pressure to 0.4~0.5MPa, control the distance between the spray gun and the surface of the glass or ceramic sample to 15~20cm, and spray for 2~3 minutes; finally, place the glass or ceramic sample in an oven at 60~80℃ for 5~10 minutes to cure, and obtain a superhydrophobic pre-coating.

[0016] Furthermore, the specific method of step S4 is as follows: Divinylbenzene and zeolite were placed in a heat-collecting magnetic stirrer and heated. After vacuuming, the mixture was slowly heated to 60 degrees Celsius. Divinylbenzene was then subjected to vacuum distillation to extract high-purity divinylbenzene monomers based on their different boiling points.

[0017] Moreover, the specific steps of step S5 include: (1) dispersing 18-20 parts of high-purity divinylbenzene monomer in 1000-1500 parts of cyclohexane, adding 4-8 parts of hydrophobic silica nanoparticles, and stirring at 300-400 rpm for 20-30 minutes at 25°C; nitrogen gas is introduced during stirring to remove air from the flask; (2) after stirring completely, the stirring speed is increased to 500-600 rpm, and 1-1.5 parts of initiator boron trifluoride ether are added dropwise to the mixture obtained in step (1); (3) after reacting for 5-10 minutes, ethanol is added to terminate the reaction, the reaction product is filtered, and finally the filter cake is dried in a vacuum environment at 50-60°C to obtain PDVB-SiO2NTs composite nanotube particles.

[0018] Furthermore, the specific method of step S6 is as follows: In step S6, 2-4 parts of polydimethylsiloxane prepolymer and 0.2-0.4 parts of curing agent are dissolved in 90-100 parts of ethyl acetate, and then 2-4 parts of PDVB-SiO2NTs and 0.2-0.4 parts of multi-walled carbon nanotubes are added and dispersed in the above mixture; stir for 25-30 minutes to prepare a superhydrophobic coating.

[0019] Furthermore, the specific method for step S7 is as follows: Using a spray gun, the above superhydrophobic mixture is sprayed onto glass or ceramic samples at a pressure of 0.4-0.5 MPa and a spraying distance of 15-20 cm for 2-3 minutes; finally, it is cured in an oven at 100-110℃ for 60-90 minutes to obtain a PDMS / PDVB-SiO2NTs coating on the surface of the glass or ceramic sample.

[0020] A method for preparing a superhydrophobic coating for insulators based on micro-nano structure design is used to prepare the superhydrophobic coating for glass insulators and ceramic insulators.

[0021] The advantages and beneficial effects of this invention are as follows: 1. This invention can solve the problems of insufficient hydrophobicity, poor self-cleaning ability, and high risk of wet flashover and pollution flashover in existing RTV coatings for insulators, while simultaneously improving the mechanical strength and structural stability of the coating. In existing technologies, traditional RTV coatings for insulators often suffer from insufficient hydrophobic angle and easy accumulation of contaminants, leading to wet flashover and pollution flashover accidents. This invention addresses this problem through a targeted technique combining a low surface energy matrix and a micro / nano rough structure: using the low surface energy polymer polydimethylsiloxane as the organic matrix, SiO2 nanoparticles are mixed in the PDVB nanotube cationic polymerization reaction to generate a micro / nano-scale roughness effect, constructing a multi-scale micro / nano rough structure on the coating surface. This structure, combined with the low surface energy characteristic, results in a static contact angle ≥154° and a roll-off angle ≤2°, significantly reducing the contact area between moisture and the coating. This achieves excellent hydrophobicity and self-cleaning performance, effectively inhibiting moisture adsorption and contaminant accumulation, fundamentally reducing the risk of wet flashover and pollution flashover, and improving the operational reliability of the power system.

[0022] 2. This invention can solve the problems of poor adhesion between the existing coating and the substrate, poor wear resistance, and insufficient long-term service capability.

[0023] In existing spray coating technologies, insulator coatings are mostly bonded to the substrate surface through physical adsorption or weak chemical bonds. These coatings are prone to detachment and wear under external forces such as mechanical friction and environmental corrosion, leading to rapid degradation of hydrophobic properties and limiting long-term service capability. This invention overcomes this limitation by employing a targeted technical approach: a silane coupling agent substrate pretreatment step is added to construct a robust transitional chemical bond layer between the substrate and the coating. This bond layer effectively enhances the adhesion between the coating and the substrate, allowing the coating to maintain its structural integrity under external forces such as mechanical friction. This avoids damage to the micro / nano structure and degradation of hydrophobic properties, achieving a synergistic improvement in both mechanical and hydrophobic properties, and ensuring the insulator's superior long-term service capability under complex operating conditions.

[0024] 3. This invention can solve the problem of dielectric property degradation of existing superhydrophobic coatings and meet the requirements for long-term stable operation in high-voltage environments.

[0025] In existing technologies, some composite coatings for insulators are prone to dielectric degradation under high-voltage electric fields due to uneven dispersion of inorganic fillers or interface defects, making them unable to withstand long-term high-voltage conditions. This invention optimizes this by employing a targeted technique involving the uniform dispersion of multi-walled carbon nanotubes: Multi-walled carbon nanotube particles are uniformly dispersed within a PDMS / PDVB-SiO2NTs composite system. Utilizing the excellent electrical insulation properties and high aspect ratio of multi-walled carbon nanotubes, a continuous and dense insulating network is formed within the coating. This technical solution ensures that the coating maintains stable electrical insulation performance under high-voltage environments, meeting the electrical performance requirements for long-term insulator service.

[0026] All the above-mentioned beneficial effects are achieved based on the technical solutions specified in this invention: silane coupling agent substrate pretreatment, preparation of PDVB-SiO2NTs composite nanotubes, and dispersion doping of multi-carbon wall nanotubes, forming an insulator superhydrophobic coating with "strong interface, stable structure, and synergistic performance", which solves the core pain points of the prior art. Attached Figure Description

[0027] Figure 1 (a) SEM image of the sample obtained in Example 1 (composite nanotube superhydrophobic coating) magnified 1000 times; Figure 1 (b) SEM characterization image of the sample obtained in Example 1 (composite nanotube superhydrophobic coating) magnified 60,000 times; Figure 2 (a) SEM image of the sample obtained in Comparative Example 1 (without nanotube superhydrophobic coating) magnified 1000 times; Figure 2 (b) SEM characterization image of the sample obtained in Comparative Example 1 (without nanotube superhydrophobic coating) magnified 6000 times; Figure 3 (a) Schematic diagram of water contact angle on the surface of Comparative Example 4 (bare glass sample without coating treatment); Figure 3 (b) Schematic diagram of water contact angle on the surface of a general RTV insulator coating sample; Figure 3 (c) Schematic diagram of water contact angle on the sample surface of Example 1 (composite nanotube superhydrophobic coating); Figure 4 A schematic diagram of the water droplet rolling angle on the sample surface obtained in Example 1; Figure 5 Schematic diagram of the self-cleaning process of the sample surface obtained in Example 1; Figure 6 Changes in hydrophobic angle and roll-off angle in the wear resistance test of Example 1; Figure 7 A connection diagram of a DC flashover testing system suitable for dry, wet, and polluted conditions. Detailed Implementation

[0028] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings: A superhydrophobic coating for insulators based on micro / nano structure design comprises the following components by weight fraction: 80 parts ethanol, 4 parts silane coupling agent, 4 parts deionized water, 4 parts hydrophobic SiO2 nanoparticles, 18 parts divinylbenzene, 1000 parts cyclohexane, 1 part boron trifluoride ethyl ether, 2 parts polydimethylsiloxane, 0.2 parts polydimethylsiloxane curing agent, and 100 parts ethyl acetate.

[0029] A method for preparing a superhydrophobic coating for insulators based on micro / nano structure design includes the following steps: Step S1: Clean and dry the glass or ceramic sample for pretreatment.

[0030] The specific method for step S1 is as follows: Take glass and ceramic samples, rinse them thoroughly with sufficient deionized water to remove surface impurities, and then place them in an ultrasonic cleaning device for surface cleaning; after removal, dry them with nitrogen gas.

[0031] Step S2: Mix ethanol, deionized water, and silane coupling agent to prepare a silane coupling agent hydrolysis solution; The raw materials for preparing the silane coupling agent hydrolysis solution in step S2 are: silane coupling agent KH550, ethanol and deionized water, with a volume ratio of 1:1:18. The solution is stirred at 250 rpm for 20 minutes on a magnetic stirrer, and then left to stand for 1 hour for later use.

[0032] Step S3: Use a spray gun to spray the hydrolysis solution prepared in step S2 onto the surface of the glass or ceramic sample, and then send the glass or ceramic sample into an oven for curing treatment to obtain a superhydrophobic pre-coating. The specific method for step S3 is as follows: Using a 1mm diameter gravity spray gun, adjust the spraying pressure to 0.4MPa, control the distance between the spray gun and the surface of the glass or ceramic sample to 15cm, and spray for 3 minutes; finally, place the glass or ceramic sample in a 110℃ oven to cure for 10 minutes to obtain a superhydrophobic pre-coating.

[0033] Step S4: Divinylbenzene is subjected to vacuum distillation to extract high-purity divinylbenzene monomer.

[0034] The specific method for step S4 is as follows: Divinylbenzene and zeolite were placed in a heat-collecting magnetic stirrer and heated. After vacuuming, the mixture was slowly heated to 60 degrees Celsius. Divinylbenzene was then subjected to vacuum distillation to extract high-purity divinylbenzene monomers based on their different boiling points.

[0035] Step S5: After thoroughly mixing high-purity divinylbenzene monomer, hydrophobic SiO2 nanoparticles and cyclohexane, add boron trifluoride diethyl ether to initiate the nanotube synthesis reaction to achieve the directional design and controllable construction of micro and nano structures; after the reaction is completed, filter, and the filter cake is dried under vacuum to obtain composite nanotube particles. The specific steps of step S5 include: (1) Disperse 18 parts of high-purity divinylbenzene monomer in 1000 parts of cyclohexane, add 4 parts of hydrophobic silica nanoparticles, and stir at 300~400 rpm for 20 minutes at 25°C; during the stirring process, nitrogen gas is introduced to remove the air in the flask, the purpose of which is to make these nano-sized silica particles evenly dispersed and not agglomerated, becoming independent nano-sized core sites, laying the foundation for the subsequent directional formation of nanotube structures, and ensuring that each core site can be evenly distributed in the PDVB nanotube system to be formed; (2) After the mixture is thoroughly stirred, the stirring speed is increased to 500-600 rpm, and 1 part of boron trifluoride diethyl ether initiator is added dropwise to the mixture. The initiator will cause the divinylbenzene monomer to polymerize only on the surface and around the silica nanoparticles. The monomer gradually polymerizes around the nano core site, and finally forms a multi-scale micro-nano rough structure with PDVB as a nano-scale tubular skeleton, SiO2 nanoparticles uniformly distributed on the surface of the tube and the surrounding micron-scale protrusions, realizing the directional design and controllable construction of the structure. (3) After the reaction is 5 minutes, ethanol is added to terminate the reaction. The reaction product is filtered (to remove unreacted initiator and monomer), and finally the filter cake is dried in a vacuum environment at 60°C to obtain PDVB-SiO2NTs composite nanotube particles.

[0036] This step involves designing and constructing the target micro / nano structure by controlling the material ratio, stirring conditions, and polymerization reaction process.

[0037] Step S6: Mix composite nanotube particles, multi-walled carbon nanotubes, polydimethylsiloxane and its curing agent with ethyl acetate to prepare a superhydrophobic coating.

[0038] The specific method for step S6 is as follows: In step S6, 2 parts of polydimethylsiloxane prepolymer and 0.2 parts of curing agent are dissolved in 100 parts of ethyl acetate, and then 2 parts of PDVB-SiO2NTs and 0.2 parts of multi-walled carbon nanotubes are added and dispersed in the above mixture; stir for 30 minutes to prepare a superhydrophobic coating.

[0039] Step S7: Spray the superhydrophobic coating onto the surface of the silanized glass or ceramic sample, and cure it in an oven to obtain a superhydrophobic coating on the surface of the glass or ceramic sample.

[0040] The specific method for step S7 is as follows: The superhydrophobic mixture was sprayed onto glass or ceramic samples for 3 minutes at a spray gun under a pressure of 0.4 MPa and a spraying distance of 15 cm. Finally, it was cured in an oven at 110°C for 60 minutes to obtain a PDMS / PDVB-SiO2NTs coating on the surface of the glass or ceramic samples.

[0041] Example 1 A method for preparing a superhydrophobic coating for insulators based on micro / nano structure design is as follows: Step S1: Cleaning and drying pretreatment of glass and ceramic samples. Take glass and ceramic samples, rinse thoroughly with sufficient deionized water to remove surface impurities, and then place them in an ultrasonic cleaning device for surface cleaning; after removal, blow them dry with nitrogen gas.

[0042] Step S2: Preparation of pre-coating hydrolysate. Prepare a silane coupling agent hydrolysate solution by mixing ethanol, deionized water, and silane coupling agent, and set aside. The raw materials for preparing the silane coupling agent hydrolysate solution are KH550, ethanol, and deionized water in a volume ratio of 1:1:18. Stir at 250 rpm for 20 minutes on a magnetic stirrer, then let stand for 1 hour.

[0043] Step S3: Pre-coating spraying. The hydrolyzed solution is sprayed onto the sample surface using a spray gun to form a base coat. The sample is then placed in an oven for curing. A 1mm diameter gravity spray gun is used, with the spraying pressure adjusted to 0.4MPa, the distance between the spray gun and the sample surface controlled at 15cm, and the spraying time 3 minutes. Finally, the sample is placed in a 110℃ oven for curing for 10 minutes to obtain the superhydrophobic pre-coating.

[0044] Step S4: High-purity divinylbenzene monomer purification by distillation. Divinylbenzene is subjected to vacuum distillation to extract high-purity divinylbenzene monomer. Divinylbenzene and zeolite are placed in a heat-collecting magnetic stirrer and heated under vacuum. The mixture is then slowly heated to 60 degrees Celsius, and high-purity divinylbenzene monomer is extracted according to different boiling points.

[0045] Step S5: In-situ synthesis and post-processing of composite nanotubes. Divinylbenzene monomer, hydrophobic SiO2 nanoparticles, and cyclohexane were thoroughly stirred until homogeneous. Boron trifluoride diethyl ether was then added to initiate the nanotube synthesis reaction. After the reaction, the mixture was filtered, and the filter cake was vacuum-dried to obtain composite nanotube particles. 18 parts of divinylbenzene monomer were dispersed in 1000 parts of cyclohexane, and 4 parts of hydrophobic silica nanoparticles were added. The mixture was stirred at 300-400 rpm for 20 minutes at 25°C, with nitrogen purging the flask to remove air during stirring. After homogeneous stirring, the stirring speed was increased to 500-600 rpm, and 1 part of boron trifluoride diethyl ether was added dropwise as the initiator. After 5 minutes, the reaction was terminated with ethanol. The reaction product was filtered to remove residual initiator and monomer, and then vacuum-dried at 60°C to obtain PDVB-SiO2NTs nanotube particles.

[0046] Step S6: Final formulation of the superhydrophobic coating. The composite nanotube particles, polydimethylsiloxane (PDMS), and its curing agent are mixed with ethyl acetate to prepare the superhydrophobic coating. Two parts of the PDMS prepolymer and 0.2 parts of the curing agent are dissolved in 100 parts of ethyl acetate, and then two parts of the PDVB-SiO2NTs composite nanotube particles are added and dispersed in the above mixture. Step S7: Construction and curing of the superhydrophobic coating. After stirring the superhydrophobic coating for 30 minutes, the superhydrophobic coating was sprayed onto the silanized sample surface on the glass and ceramic substrates using a spray gun at a pressure of 0.4 MPa and a spraying distance of 15 cm for 3 minutes. Finally, it was cured in an oven at 110℃ for 60 minutes to obtain the composite nanotube coating.

[0047] A method for preparing a superhydrophobic coating for insulators based on micro-nano structure design is used to prepare a superhydrophobic coating for glass insulators and ceramic insulators.

[0048] Figure 1 (a) is a 1000x magnified SEM image of the glass sample obtained in Example 1 (PDMS / PDVB-SiO2NTs superhydrophobic coating). The coating surface shows irregularly distributed micron-sized protrusions with a large number of micron-sized pores between adjacent protrusions. This micro-nano binary composite structure significantly reduces the liquid-solid contact area by constructing a gas-solid composite interface. Figure 1 (b) A 60,000x magnified SEM image of the glass sample obtained in Example 1, showing a regular nanotube structure with a diameter distribution in the range of 100-150 nm. The introduction of nanotubes significantly enhances the surface roughness of the coating, compared to... Figure 2 (a) and Figure 2(b) Comparative Example 1 (SiO2 superhydrophobic coating) shows a more significant micro-nano composite structure. This result indicates that PDVB-SiO2NTs, by constructing additional nanoscale roughness, work synergistically with the micron-scale structure to jointly build a micro-nano binary rough structure system for the superhydrophobic surface, providing a structural basis for improving the hydrophobic performance of the coating.

[0049] Figure 3 (a) The water contact angle of the glass sample in Comparative Example 4 (untreated original sample) is 70.3°; Figure 3 (b) The water contact angle of the RTV coating is 121.2°; Figure 3 (c) shows the hydrophobic angle of Example 1, with a contact angle reaching 155.2°. Figure 4 The roll-off angle for Example 1 is 1.5°. The surface prepared in Example 1 exhibits excellent superhydrophobic properties, and water droplets roll off the surface very easily. In contrast, the untreated bare glass surface in Comparative Example 4 only exhibits a contact angle of 70.3° and a relatively large roll-off angle of 30.5°, displaying typical hydrophilicity and high adhesion characteristics. This comparison fully demonstrates the significant advantages of the coating constructed in Example 1 in terms of superhydrophobic properties.

[0050] Figure 5 This is a self-cleaning capability test for Example 1. The superhydrophobic surface was placed at a 5° tilt angle, and sand was spread on the coating surface to simulate actual dirt accumulation conditions. The experimental results show that water droplets can quickly roll off the coating surface, effectively removing the attached sand particles, indicating that the superhydrophobic coating has excellent self-cleaning performance. This characteristic is of great significance for improving the anti-fouling ability of outdoor insulator surfaces.

[0051] Figure 6 The wear resistance test for Example 1 was conducted. The coated sample was inverted onto 800-grit sandpaper and a 100g weight was placed on it. The sample was then pushed laterally by 10 cm and then moved longitudinally by 10 cm, constituting one wear cycle. The hydrophobicity of the coating was tested every five cycles, and changes in hydrophobicity were observed. After 50 wear cycles, the hydrophobic angle still reached 150°, less than 3°, meeting the superhydrophobic requirement. This indicates that the coating possesses excellent wear resistance and has engineering application value for significantly improving the actual service reliability and durability of insulators.

[0052] To systematically study the effect of multi-walled carbon nanotube (MWCNT) content on the surface flashover properties of composite materials, this invention prepared four groups of samples (Examples 2-5) with MWCNT mass fractions of 5%, 10%, 15%, and 20% (ratio to SiO2 mass fraction), respectively, to compare and analyze their flashover characteristics.

[0053] Example 2 Example 2: Steps S1-S5 and S7 were performed, and 0.1 parts of multi-carbon wall nanotube particles were added in step S6. The DC flashover voltage of the sample was tested (dry flashover, wet flashover, and contaminated flashover).

[0054] Example 3 Example 3: Steps S1-S5 and S7 were performed, and 0.2 parts of multi-carbon wall nanotube particles were added in step S6. The DC flashover voltage of the sample was tested (dry flashover, wet flashover, and contaminated flashover).

[0055] Example 4 Example 4: Steps S1-S5 and S7 were performed, and 0.3 parts of multi-carbon wall nanotube particles were added in step S6. The sample was then subjected to DC flashover voltage testing (dry flashover, wet flashover, and contaminated flashover).

[0056] Example 5 Example 5: Steps S1-S5 and S7 were performed, and 0.4 parts of multi-carbon wall nanotube particles were added in step S6. The DC flashover voltage of the sample was tested (dry flashover, wet flashover, and contaminated flashover).

[0057] To systematically evaluate the independent contributions and synergistic effects of key components (PDVB nanotubes, PDVB-SiO2 composite nanotubes) and core processes (silane pretreatment) on coating performance, this invention designed a series of control experiments to precisely pinpoint the mechanisms of action of each element, as detailed below: Four comparative examples were prepared: 1. A PDMS / SiO2 composite coating without PDVB NTs (Comparative Example 1), used to evaluate the enhancement effect of SiO2 on hydrophobic properties; 2. A pure PDMS coating without PDVB-SiO2NTs (Comparative Example 2), to define the hydrophobic performance benchmark of the PDMS matrix; 3. A PDMS / PDVB-SiO2NTs composite coating without silane pretreatment (Comparative Example 3), used to compare the effect of silane pretreatment on coating adhesion and abrasion resistance; 4. An original substrate sample without any coating or pretreatment (Comparative Example 4), serving as a blank control for full performance testing.

[0058] By comparing the hydrophobic properties of the examples with those of Comparative Examples 1, 2, and 4, the hydrophobic gain of SiO2, the synergistic effect of PDVB-SiO2 composite nanotubes, and the independent contribution of chemical modification (low surface energy components) to hydrophobic properties can be clearly identified. Furthermore, by comparing the wear resistance of the examples with that of Comparative Example 3, the key role of the silane pretreatment layer in strengthening the bond between the coating and the substrate can be clearly identified, providing data support for the synergistic optimization of various components and processes.

[0059] Comparative Example 1 Comparative Example 1 was prepared by performing steps S1-S3 and S7. In step S6, hydrophobic silica particles, polydimethylsiloxane and its curing agent were mixed with ethyl acetate to prepare a superhydrophobic coating. The resulting nanotube-free superhydrophobic coating was then subjected to hydrophobicity testing and SEM testing.

[0060] Comparative Example 2 Comparative Example 2 was performed, with steps S1-S3 and S7. In step S6, only 2 parts of polydimethylsiloxane prepolymer and 0.2 parts of curing agent were dissolved in 100 parts of ethyl acetate to obtain a coating containing only polydimethylsiloxane. A hydrophobic angle test was then conducted for comparison.

[0061] Comparative Example 3 Comparative Example 3 was performed using steps S1 and S4-S7, which involved removing the pre-silane coupling agent coating. Hydrophobicity and abrasion resistance tests were then conducted for comparison.

[0062] Comparative Example 4 Comparative Example 4: only step S1 was performed, that is, only the glass / ceramic sample was ultrasonically cleaned and the bare sample was compared with hydrophobicity test and flashover test.

[0063] The water contact angles of the samples obtained in Examples 1-5 and Comparative Examples 1-4 were measured. The water contact angle measurements included measuring the static contact angle and roll-off angle of the water droplets on the surface. The measurement results are listed in Table 1.

[0064] Table 1. Static contact angle and roll-off angle data for Examples 1-5 and Comparative Examples 1-4;

[0065] Based on the data in Table 1, it is clear that the untreated original glass / ceramic samples in Comparative Example 4 are all hydrophilic materials (water contact angle less than 90°); the pure PDMS substrate coating in Comparative Example 2 has a certain degree of hydrophobicity, but the water contact angle is only 120-130°, failing to achieve a superhydrophobic effect; the PDMS / SiO2 coating in Comparative Example 1 shows that after the single PDMS coating is combined with hydrophobic nano-silica, the contact angle exceeds 150°, and the roll-off angle decreases to 2°. Examples 1-5 are all composite nanotube superhydrophobic coatings containing PDMS / PDVB-SiO2NTs. The hydrophobic angles show that the superhydrophobic coatings based on micro / nano structure design further improve the superhydrophobic effect, all reaching 154-155°.

[0066] In summary, hydrophobic nano-silica particles serve as the core carrier for superhydrophobic properties, while PDVB nanotubes act as structural reinforcing agents for the superhydrophobic coating. When combined, the contact angle increases to over 154°, achieving a superhydrophobic effect, while the roll-off angle decreases to 1.5°. Their core contribution is the reinforcement of the micro / nano-level rough structure. Thus, it is evident that the contributions of hydrophobic nano-silica particles, PDVB nanotubes, and PDMS to the superhydrophobic coating differ, and the synergistic effect of the combined system is superior to that of a single component.

[0067] Abrasion resistance tests were conducted on Examples 1-5 and Comparative Example 3 (sample without pre-coating). A sandpaper abrasion test was performed, inverting the coated sample onto 800-grit sandpaper, placing a 100g weight on the sample, and then moving the sample laterally 10 cm followed by longitudinally 10 cm, constituting one abrasion cycle. After 50 abrasion cycles, the hydrophobic angle of Examples 1-5 did not drop below 150°, and the roll-off angle was less than 3°. Figure 6 The results of the wear resistance test for Example 1 are shown; while for Comparative Example 2, the exposed surface of the sample was exposed after the first wear cycle, and the hydrophobic angle of the exposed part dropped to 70°, losing its superhydrophobic properties. It can be seen that the pre-coating of the silane coupling agent on the glass and ceramic surfaces has a great influence on the improvement of wear resistance.

[0068] In the KH550 molecule, the inorganic-terminated triethoxysilyl group (-Si(OC2H5)3) undergoes hydrolysis under the influence of trace amounts of moisture in the environment. The ethoxy group (-OC2H5) is gradually replaced by a hydroxyl group, generating a highly reactive silanol group (-Si(OH)3), while releasing ethanol. Subsequently, the silanol group of KH550 forms a stable Si-O-substrate covalent bond with the hydroxyl group abundant on the surface of the glass / ceramic substrate treated with deionized water through a dehydration condensation reaction, achieving chemical anchoring of KH550 on the substrate surface and constructing the first chemical bond connection of "substrate-KH550". The PDMS coating is usually hydroxyl-terminated (terminal group is -Si-OH). The lone pair electrons in the amino group of KH550 can form a strong hydrogen bond with the hydrogen atom of the hydroxyl group of PDMS. Under heat curing (usually 80-120℃), a further dehydration condensation reaction occurs, forming a -NHO-Si- covalent bond (the NH bond of the amino group and the OH group of PDMS). (By dehydration bonding), KH550 and PDMS coating are tightly connected, ultimately constructing a complete chemical bonding system of "glass / ceramic-Si-O-KH550-NHO-Si-PDMS". This transforms the physical adsorption of the coating and substrate into a strong chemical bond. The physical adsorption of the coating relies solely on van der Waals forces, resulting in extremely low binding energy (approximately 0.1-1 kcal / mol), while the covalent bond binding energy can reach 50-100 kcal / mol. This increases the interfacial adhesion by tens of times, fundamentally solving the problem of coatings easily peeling off from the substrate surface.

[0069] The samples obtained from Examples 1 to 5 and Comparative Example 4 (untreated original sample) were subjected to DC flashover voltage tests. The flashover voltage tests included flashover tests in a dry state, flashover tests in a fully wetted state, and flashover tests in a fully wetted state after being treated with contamination.

[0070] A DC flashover testing system suitable for dry, wet, and polluted conditions, such as Figure 7 As shown, it includes: a high-voltage DC power supply, a controllable environmental test chamber, a high-frequency current transformer, an oscilloscope, a misting humidification device, and a high-speed camera; The high-voltage DC power supply provides a stable and controllable DC voltage for flashover testing. The controllable environment test chamber is used to construct three standardized test environments and ensures the consistency and repeatability of test conditions through a built-in humidity monitoring module. The high-frequency current transformer can capture the partial discharge signal at the moment of flashover of the sample in real time. The discharge signal is simultaneously acquired using an oscilloscope and the flashover voltage value and discharge signal waveform are accurately recorded. The ultrasonic atomizing humidifier is specially designed to provide uniform water mist for wet and polluted tests, with the spray flow rate controlled at 0.5 kg / (h·m³). 3In conjunction with the humidity monitoring module of the test chamber, a closed-loop control is formed to ensure that the sample surface is saturated with moisture. A high-speed camera synchronizes with the oscilloscope trigger signal at a frame rate of ≥1000 frames / second to visually record the discharge path and arc shape at the moment of flashover. Metal clamps and brass plate electrodes are used to horizontally fix the 50 mm × 50 mm × 1 mm sample. The electrode edges are designed with rounded corners to reduce electric field distortion. The electrode spacing is strictly set at 10 mm and the brass material ensures excellent conductivity to avoid self-discharge interference.

[0071] A high-voltage DC power supply is used to controllably supply pressure to the sample via metal clamps and brass plate electrodes. The humidity monitoring and atomization humidification device of the controllable environmental test chamber enables spray flow regulation. The instantaneous flashover discharge signal of the sample is acquired by a high-frequency current transformer and then triggers an oscilloscope to simultaneously record the flashover voltage peak and electrical signal waveform. The oscilloscope trigger signal is also linked to a high-speed camera to capture the discharge process. Finally, the two types of data work together to support subsequent statistical analysis.

[0072] The test employed a uniform voltage ramp method, with the initial voltage set at 40% of the expected flashover voltage. The voltage was then continuously increased at a linear ramp rate of 0.5 kV / s until flashover occurred, and the flashover voltage value was recorded. Each sample was tested 10 times, with a 5-minute interval between adjacent tests to ensure sufficient dissipation of air ionization caused by the discharge. The Weibull distribution method was used to statistically analyze the surface flashover characteristics of composite superhydrophobic coatings with different multi-walled carbon nanotube contents.

[0073] For flashover testing under wet conditions, an ultrasonic atomizing device was used to humidify the sample, with the spray flow rate controlled at 0.5 kg / (h·m). 3 This ensures that the water mist is evenly distributed within the test chamber. Continuous monitoring of ambient humidity changes is maintained to ensure the sample surface reaches a saturated, moist state.

[0074] For flashover testing under polluted conditions, sodium chloride and diatomaceous earth were selected as contaminants, with a salt density of 0.1 mg / cm³. 2 Ash density 0.6 mg / cm³ 2 The contaminant layer was prepared in the specified proportions, thoroughly mixed, and then evenly spread onto the sample surface using a standard sieve, with strict control over the quality of the adhering contaminant. The sample was then placed in an artificial test chamber for wetting and flashover tests.

[0075] After all state tests were completed, flashover voltage data of composite superhydrophobic coating samples with different multi-walled carbon nanotube contents were collected. Statistical analysis was performed using the Weibull distribution method to calculate characteristic flashover voltages and dispersion parameters. Discharge images captured by a high-speed camera were used to assist in the analysis of the surface flashover mechanism, and a complete test report was finally generated.

[0076] Table 2 Surface flashover voltage test results of Examples 1-5 and Comparative Example 4

[0077] Table 2 shows the flashover voltage test data of two typical insulator substrates, glass and ceramic, under dry, wet, and polluted conditions. The insulation performance differences of Comparative Example 4 (the original sample without superhydrophobic coating) and five sets of coated examples (superhydrophobic coatings with multi-walled carbon nanotube additions of 0 wt%, 5 wt%, 10 wt%, 15 wt%, and 20 wt%) are systematically compared. The results intuitively demonstrate the significant effect of the superhydrophobic coating on improving the flashover voltage of the insulation material, and its performance advantages are particularly prominent in harsh service environments such as wet flashover and pollution flashover.

[0078] Regarding the core concern of flashover protection, the coating achieved a breakthrough performance improvement: in the glass substrate, the flashover voltage of Comparative Example 3 was only 1.95 kV / cm, while all examples with the coating reached above 7.03 kV / cm, with Example 3 showing the best performance, with a flashover voltage as high as 9.56 kV / cm, an improvement of over 390% compared to the comparative example; the flashover performance of the ceramic substrate was also significantly improved, from 2.94 kV / cm in Comparative Example 3 to a maximum of 9.3 kV / cm (Example 3), an improvement of approximately 216%. This result fully demonstrates that the superhydrophobic coating can fundamentally solve the problem of flashover in insulators by inhibiting the formation of continuous conductive paths after contamination and moisture.

[0079] In the field of wet flashover protection, the coating exhibits stable optimization effects: the wet flashover voltage of glass and ceramic substrates is generally increased from about 7.8 kV / cm in the comparative example to more than 9.0 kV / cm in most embodiments, with the wet flashover voltage of Examples 2 and 3 both reaching more than 9.4 kV / cm. This demonstrates that the excellent hydrophobic properties of the coating can effectively prevent the formation of surface water film in rainy environments, thereby maintaining insulation strength.

[0080] Compared to the significant improvements in wet flashover and pollution flashover, the optimization of dry flashover performance is relatively limited and fluctuates to some extent. For example, the dry flashover voltage of the various ceramic substrate embodiments fluctuates between 11.84 and 16.33 kV / cm, which is not much different from the 12.06 kV / cm of Comparative Example 3. This is mainly because the insulator substrate itself already has good insulation performance in a dry environment. The micro-nano structure and low surface energy characteristics of the coating are more focused on improving insulation strength in harsh working conditions.

[0081] In summary, Example 3 exhibits the best and most stable overall performance on both substrates, with the highest wet flashover and pollution flashover voltages among all groups, corresponding to the optimal formulation process. Overall, this superhydrophobic coating technology effectively enhances the flashover resistance of insulator materials in real-world complex environments, achieving a breakthrough, especially in the critical area of ​​pollution flashover protection, providing reliable technical support for the safe and stable operation of high-voltage power equipment.

[0082] It should be emphasized that the embodiments described in this invention are illustrative rather than limiting. Therefore, this invention includes, but is not limited to, the embodiments described in the specific implementation. Any other implementations derived by those skilled in the art based on the technical solutions of this invention are also within the scope of protection of this invention.

Claims

1. A superhydrophobic coating for insulators based on micro / nano structure design, characterized in that: Components including the following weight fractions: Ethanol 70-80 parts, silane coupling agent 4-8 parts, deionized water 2.4-4 parts, hydrophobic SiO2 nanoparticles 4-8 parts, divinylbenzene 18-20 parts, cyclohexane 1000-1500 parts, boron trifluoride ethyl ether 1-1.5 parts, polydimethylsiloxane 2-4 parts, polydimethylsiloxane curing agent 0.2-0.4 parts, ethyl acetate 90-100 parts.

2. A method for preparing a superhydrophobic coating for insulators based on micro / nano structure design, characterized in that: Includes the following steps: Step S1: Clean and dry the glass or ceramic sample for pretreatment; Step S2: Mix ethanol, deionized water, and silane coupling agent to prepare a silane coupling agent hydrolysis solution; Step S3: Use a spray gun to spray the hydrolysis solution prepared in step S2 onto the surface of the glass or ceramic sample, and then send the glass or ceramic sample into an oven for curing treatment to obtain a superhydrophobic pre-coating. Step S4: Divinylbenzene is subjected to vacuum distillation to extract high-purity divinylbenzene monomer; Step S5: After thoroughly mixing high-purity divinylbenzene monomer, hydrophobic SiO2 nanoparticles and cyclohexane, boron trifluoride diethyl ether is added to initiate the nanotube synthesis reaction, realizing the directional design and controllable construction of micro and nano structures; after the reaction is completed, the mixture is filtered, and the filter cake is dried under vacuum to obtain composite nanotube particles. Step S6: Mix composite nanotube particles, multi-walled carbon nanotubes, polydimethylsiloxane, polydimethylsiloxane curing agent and ethyl acetate to prepare a superhydrophobic coating; Step S7: Spray the superhydrophobic coating onto the surface of the silanized glass or ceramic sample, and cure it in an oven to obtain a superhydrophobic coating on the surface of the glass or ceramic sample.

3. The method for preparing a superhydrophobic coating for an insulator based on a micro / nano structure design according to claim 2, characterized in that: The specific method for step S1 is as follows: Take glass and ceramic samples, rinse them thoroughly with sufficient deionized water to remove surface impurities, and then place them in an ultrasonic cleaning device for surface cleaning; after removal, dry them with nitrogen gas.

4. The method for preparing a superhydrophobic coating for an insulator based on a micro / nano structure design according to claim 2, characterized in that: The raw materials for preparing the silane coupling agent hydrolysis solution in step S2 are: silane coupling agent KH550, ethanol and deionized water, with a volume ratio of 1:(0.6~2):(17~18). The solution is stirred at 250~300 rpm for 20~30 minutes on a magnetic stirrer, and then left to stand for 1~2 hours for later use.

5. The method for preparing a superhydrophobic coating for an insulator based on a micro / nano structure design according to claim 2, characterized in that: The specific method for step S3 is as follows: Use a gravity spray gun with a nozzle diameter of 1~1.5mm, adjust the spraying pressure to 0.4~0.5MPa, control the distance between the spray gun and the surface of the glass or ceramic sample to 15~20cm, and spray for 2~3 minutes; finally, place the glass or ceramic sample in an oven at 60~80℃ for 5~10 minutes to cure, and obtain a superhydrophobic pre-coating.

6. The method for preparing a superhydrophobic coating for an insulator based on a micro / nano structure design according to claim 2, characterized in that: The specific method for step S4 is as follows: Divinylbenzene and zeolite were placed in a heat-collecting magnetic stirrer and heated. After vacuuming, the mixture was slowly heated to 60 degrees Celsius. Divinylbenzene was then subjected to vacuum distillation to extract high-purity divinylbenzene monomers based on their different boiling points.

7. The method for preparing a superhydrophobic coating for an insulator based on a micro / nano structure design according to claim 2, characterized in that: The specific steps of step S5 include: (1) Dispersing 18-20 parts of high-purity divinylbenzene monomer in 1000-1500 parts of cyclohexane, adding 4-8 parts of hydrophobic silica nanoparticles, and stirring at 300-400 rpm for 20-30 minutes at 25°C; nitrogen gas is introduced during stirring to remove air from the flask; (2) After stirring completely and evenly, the stirring speed is increased to 500-600 rpm, and 1-1.5 parts of boron trifluoride diethyl ether initiator are added dropwise to the mixture obtained in step (1); (3) After reacting for 5-10 minutes, ethanol is added to terminate the reaction, the reaction product is filtered, and finally the filter cake is dried in a vacuum environment at 50-60°C to obtain PDVB-SiO2NTs composite nanotube particles.

8. The method for preparing a superhydrophobic coating for an insulator based on a micro / nano structure design according to claim 2, characterized in that: The specific method for step S6 is as follows: In step S6, 2-4 parts of polydimethylsiloxane prepolymer and 0.2-0.4 parts of curing agent are dissolved in 90-100 parts of ethyl acetate, and then 2-4 parts of PDVB-SiO2 NTs and 0.2-0.4 parts of multi-walled carbon nanotubes are added and dispersed in the above mixture; stir for 25-30 minutes to prepare a superhydrophobic coating.

9. The method for preparing a superhydrophobic coating for an insulator based on a micro / nano structure design according to claim 2, characterized in that: The specific method for step S7 is as follows: Using a spray gun, the above superhydrophobic mixture is sprayed onto glass or ceramic samples at a pressure of 0.4~0.5 MPa and a spraying distance of 15~20 cm for 2~3 minutes; finally, it is cured in an oven at 100~110℃ for 60~90 minutes to obtain a PDMS / PDVB-SiO2 NTs coating on the surface of the glass or ceramic sample.

10. The application of the superhydrophobic coating obtained by the method for preparing a superhydrophobic coating for insulators based on micro-nano structure design according to any one of claims 1-9 in the preparation of glass insulators and ceramic insulators.

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