A high-voltage transmission line anti-condensation and anti-icing self-cleaning coating and a preparation method thereof

Abstract

This invention belongs to the field of coating preparation technology and provides a self-cleaning coating for high-voltage transmission lines to prevent condensation and icing, as well as its preparation method. After curing, the coating forms a base layer, an intermediate functional layer, and a top layer sequentially arranged from the inside out on the surface of the conductor. The base layer is a hybrid binder layer composed of silane and inorganic components. The intermediate functional layer uses a siloxane elastomer as the continuous phase and contains phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, core-shell dielectric particles, and a low surface energy fluid phase. The dielectric particles are enriched at the interface between the intermediate layer and the top layer. The top layer is a low-modulus siloxane elastomer containing a hierarchical rough structure composed of hydrophobically modified nanoparticles and micron-sized particles, and also contains low surface energy migration components. This coating possesses comprehensive anti-condensation, anti-icing, and self-cleaning properties.

Description

Technical Field

[0001] This invention belongs to the field of coating preparation technology, and relates to a self-cleaning coating for high-voltage transmission lines that prevents condensation and icing, and its preparation method. Background Technology

[0002] High-voltage transmission lines operate outdoors for extended periods, exposed to factors such as humid heat cycles, smog and salt pollution, rain condensation, and low-temperature freezing. Condensation or discrete water droplets easily form on the conductor surface, and under specific meteorological conditions, frost and ice can further develop. Condensation alters the wetting and electric field distribution on the conductor surface. Water droplets, under the influence of a strong electric field, are prone to stretching and deformation, creating localized field enhancement in the three-phase contact area. This induces corona discharge, partial discharge, and electrical erosion, leading to problems such as noise, energy loss, and reduced insulation margin. Ice accumulation significantly increases conductor load and the risk of wind-induced vibration, causing changes in sag, increased galloping, abnormal stress on fittings, and even line breakage and tripping, severely impacting the safe and stable operation of transmission lines.

[0003] Existing methods for de-icing transmission lines mainly include manual or mechanical knocking, heating with de-icing devices, electric current de-icing, and external heating sources. However, these methods generally suffer from drawbacks such as high construction difficulty, high energy consumption, strong constraints from power outages or restrictions, high safety risks, and difficulty in continuous implementation under complex terrain and severe weather conditions. To reduce operation and maintenance costs, passive anti-icing and anti-fouling technologies based on coatings have attracted attention, such as silicone rubber-based hydrophobic coatings, superhydrophobic surfaces constructed with micro-nano rough textures, and surface modification systems incorporating photothermal components. However, single hydrophobic or superhydrophobic strategies often focus on changing the wetting morphology, making it difficult to simultaneously address long-term anti-condensation and low ice adhesion under low temperature and high humidity conditions. Micro-nano structures are easily worn and passivated by wind and sand erosion, ice peeling, maintenance wiping, and contamination deposition, leading to a decline in hydrophobicity and self-cleaning performance. At the same time, for high-voltage and strong electric field conditions, some coatings may still experience problems such as residual microdroplets, three-phase line field concentration, and enhanced corona discharge under humid conditions, even causing localized electrolytic erosion and interface aging of the coating. Introducing conductive absorbing materials into photothermal enhanced coatings may lead to electrical reliability issues and partial discharge risks. Phase change energy storage composite coatings are often constrained by factors such as low thermal conductivity, discontinuous heat transfer paths, and interface peeling and micro-defects caused by phase change cycles, which affect de-icing response and long-term insulation life. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a self-cleaning coating for high-voltage transmission lines to prevent condensation and icing, and its preparation method. After curing, the coating forms a composite structure consisting of a base layer, an intermediate functional layer, and a top layer. The base layer achieves strong adhesion. The intermediate functional layer incorporates phase-change microcapsules, light-absorbing particles, oriented insulating and thermally conductive fillers, and interface-enriched core-shell dielectric particles, and contains a low surface energy fluid phase. The top layer constructs a low-modulus, graded, rough, superhydrophobic surface and contains migrating components. Through pretreatment, layered application, orientation control, interface enrichment, and curing, a stable protective layer is obtained, thereby meeting the needs of actual production.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a self-cleaning coating for high-voltage transmission lines that prevents condensation and icing, the coating comprising a base layer, an intermediate functional layer and a top layer stacked sequentially from the inside to the outside after curing on the surface of the conductor;

[0007] The base coating is formed by applying a base coating to the surface of the wire and curing it. The base coating contains alkoxysilane, silica sol and tetraethoxysilane in a mass ratio of (1-3):(4-8):(1-3).

[0008] The intermediate functional layer uses siloxane elastomer as the continuous phase and includes phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, core-shell dielectric particles, and a low surface energy fluid phase. The low surface energy fluid phase is silicone oil and / or fluorosilicone oil. The core-shell dielectric particles are enriched in the interface region between the intermediate functional layer and the topcoat layer. The mass ratio of siloxane elastomer, phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, core-shell dielectric particles, and low surface energy fluid phase is (50-70):(15-25):(2-6):(6-12):(1-3):(1-5).

[0009] The surface coating uses methyl vinyl silicone rubber as the continuous phase, contains micro / nano-level rough components composed of hydrophobic modified nanoparticles and micron-sized inorganic particles, and contains polydimethylsiloxane. The mass ratio of methyl vinyl silicone rubber, hydrophobic modified nanoparticles, micron-sized inorganic particles and polydimethylsiloxane is (60-80):(3-10):(5-15):(2-8).

[0010] Preferably, the alkoxysilane in the base coating is selected from one or more of γ-glycidyl ether propyltrimethoxysilane, vinyltriethoxysilane, and aminopropyltriethoxysilane; the cured thickness of the base coating is 5-50 μm.

[0011] Preferably, the siloxane elastomer of the intermediate functional layer comprises vinyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, platinum-based catalyst, and 1-ethynyl-1-cyclohexanol, wherein the mass ratio of vinyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, platinum-based catalyst, and 1-ethynyl-1-cyclohexanol is 100:(2-10):(0.01-0.05):(0.1-1); and the cured thickness of the intermediate functional layer is 80-400 μm.

[0012] Preferably, the phase change microcapsule is a double-shell structure microcapsule, comprising a phase change core material, an inorganic inner shell layer, and a siloxane outer shell layer; the siloxane outer shell layer contains vinyl groups and / or hydrosilane groups; the phase change temperature of the phase change core material is -5℃ to +5℃.

[0013] Preferably, the light-absorbing particles are selected from black inorganic pigment particles.

[0014] Preferably, the insulating thermally conductive filler is selected from hexagonal boron nitride and / or aluminum nitride, with a D50 of 1-60 μm; the insulating thermally conductive filler is oriented in the intermediate functional layer, and the angle between the orientation direction and the coating thickness direction is ≤30°.

[0015] Preferably, the core of the core-shell dielectric particle is selected from one or more of barium titanate, strontium titanate, titanium dioxide, zinc oxide, and silicon carbide; the shell of the core-shell dielectric particle is an insulating shell layer of silicon dioxide and siloxane; the D50 of the core-shell dielectric particle is 50-500 nm; the interface region is the region 0-30 μm away from the interface between the intermediate functional layer and the topcoat layer, and the volume fraction of the core-shell dielectric particle in the interface region is 1.5-10 times that of the remaining regions of the intermediate functional layer.

[0016] Preferably, the hydrophobic modified nanoparticles in the surface coating are hydrophobic modified nano-silica, and the micron-sized inorganic particles are selected from one or more of silica, alumina, and boron nitride.

[0017] Preferably, the low surface energy fluid phase has a kinematic viscosity of 200-1000 mmHg at 25°C. 2 / s.

[0018] Preferably, the core-shell dielectric particles form a continuous enrichment band in the interface region, the cured thickness of the enrichment band is 2-20 μm, and the mass fraction of the core-shell dielectric particles in the enrichment band is 2-10 times that of the mass fraction of the core-shell dielectric particles in the cured intermediate functional layer.

[0019] Secondly, the present invention provides a method for preparing a self-cleaning coating for high-voltage transmission lines that prevents condensation and icing, the method comprising:

[0020] S1. Surface pretreatment of conductors: After degreasing by solvent cleaning, clean with 2-5% alkaline cleaning solution at 40-60℃ for 5-15 minutes, rinse with deionized water until neutral, and dry with hot air at 60-90℃ for 10-30 minutes.

[0021] S2. Mechanical roughening: Alumina sand with a mesh size of 80-120 is used for sandblasting. The sandblasting pressure is 0.30-0.60MPa, the nozzle distance is 100-200mm, and the sandblasting time is 30-120s, so that the surface roughness Ra of the conductor is 1.0-4.0μm.

[0022] S3. Primer application and curing: Apply the primer coating and let it cure to a thickness of 5-50μm. After leveling at room temperature for 5-20 minutes, cure at 60-120℃ for 10-60 minutes to form the primer layer.

[0023] S4. Application and Orientation of Intermediate Functional Layer: Phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, and core-shell dielectric particles are dispersed in a siloxane system and applied to form an intermediate functional layer, which is cured to a thickness of 80-400 μm. During the leveling stage of the intermediate functional layer, a wire is used as the inner electrode and a coaxially arranged grounded metal mesh tube is used as the outer electrode. An alternating electric field is applied with an electric field strength of 1.0-4.0 kV / mm, a frequency of 1-20 kHz, and an application time of 60-300 s.

[0024] S5. Pre-curing: Pre-cur the intermediate functional layer at 40-80℃ for 10-40 minutes;

[0025] S6. Apply interface transition slurry: Apply interface transition slurry within 1-10 minutes after pre-curing to form an enrichment zone. The interface transition slurry contains core-shell dielectric particles and is then cured at 80-140℃ for 10-120 minutes.

[0026] S7. Topcoat application and curing: Apply the topcoat to achieve a curing thickness of 20-150μm. After leveling at room temperature for 5-30 minutes, cure at 80-140℃ for 10-120 minutes to form a self-cleaning coating for high-voltage transmission lines that prevents condensation and icing.

[0027] After cleaning, oxide film removal, and roughening, the surface of the metal oxide layer forms hydroxylated active sites and exposes more reactive areas. The alkoxysilane in the primer hydrolyzes to generate silanols under the action of trace amounts of water. These silanols condense to form a silicon-oxygen network, while simultaneously, the silanols and hydroxyl groups on the metal oxide surface undergo dehydration condensation to form metal-oxygen-silicon bonds. Silica sol or tetraethoxysilane participates in sol-gel condensation, making the inorganic silicon-oxygen framework continuous and coupling with the interface. The intermediate functional layer uses addition-crosslinked siloxanes as the continuous phase. Vinyl-substituted polysiloxanes and hydrosilicone-containing polysiloxanes undergo hydrosilylation addition under platinum catalysis, generating silicon-carbon bonds and constructing a crosslinked network. In the double-shell phase change microcapsules, the inorganic inner shell is formed by sol-gel condensation to create a barrier layer; the siloxane outer shell containing vinyl or hydrosilicone groups can participate in hydrosilylation crosslinking and covalently anchor to the matrix, reducing interfacial slip and micropore defects caused by phase change cycling. Insulating and thermally conductive fillers such as boron nitride or aluminum nitride are oriented under the action of shear and alternating electric field, forming a more continuous heat conduction path along the thickness direction; silanization of the filler surface can introduce reactive groups, enabling them to participate in network connection and reduce interfacial thermal resistance and debonding risk.

[0028] Core-shell dielectric particles consist of a high-dielectric core and an insulating shell. The shell provides electrical isolation and inhibits interparticle conduction, while being fixed by condensation with the surrounding network through silanol or siloxane groups on the shell surface. Particles accumulate at the interface between the intermediate layer and the topcoat, forming a dielectric gradient structure that alters the potential boundary conditions near the water-gas-solid contact line, redistributes the local electric field peak distribution, and changes the local field strength required for discharge initiation. The silicone or fluorosilicone oil introduced into the intermediate layer exists as a swollen or discrete phase; molecular diffusion causes it to migrate to the surface and form a capping layer, reducing the density of effective hydrogen bond formation sites at the interface. In low-temperature environments, this mobile phase alters the fracture mode and stress transfer path of the ice-solid interface.

[0029] The topcoat is made of methyl vinyl silicone rubber, with hydrophobically modified nanoparticles and micron-sized particles forming a hierarchical rough structure and fixed by a network. Low surface energy migration components form and maintain a surface enrichment layer in the cured network, covering exposed sites on the particles and substrate, making the surface chemical composition dominated by polysiloxane or fluorosiloxane segments, thereby reducing contact line pinning and droplet retention. Interlayer bonding is mainly achieved through the interpenetration and condensation of the primer silicone network and the intermediate silicone network. At the same time, the reactive groups remaining after the intermediate pre-curing continue to undergo hydrosilylation addition during the topcoat application and post-curing stages, resulting in covalent coupling of the network at the interface. When the interface transition slurry cures, it locks the dielectric particle enrichment band into a stable gradient structure.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: The coating of the present invention constructs a composite structure of a base coating, an intermediate functional layer, and a top coating on the surface of a high-voltage transmission line. The base coating forms a stable chemical bond with the metal oxide layer through silane hydrolysis and condensation, and works synergistically with the inorganic silicon-oxygen network to improve the adhesion stability of the coating under outdoor humid and polluted conditions. The intermediate functional layer adopts an addition-crosslinked siloxane continuous phase, introduces phase change microcapsules and light-absorbing particles to form thermal response units, and establishes heat transfer channels along the thickness direction with oriented insulating and thermally conductive fillers to regulate the surface water film. The phase state and adhesion state of the icing interface; the core-shell dielectric particles are enriched in the interface region between the intermediate layer and the topcoat to form a dielectric gradient structure, which changes the potential boundary conditions near the three-phase contact line and suppresses the local electric field concentration and discharge-induced electrical erosion under humid conditions; the topcoat uses low-modulus siloxane as the matrix to construct a micro-nano hierarchical rough morphology, and combines low surface energy migration components with the low surface energy fluid phase of the intermediate layer to achieve surface energy stability and weak adhesion of pollutants, promote the migration of condensation droplets and removal of contaminants, and is suitable for long-term surface protection in the condensation and icing environment of power transmission lines. Attached Figure Description

[0031] Figure 1 A photograph of the water contact angle provided in Embodiment 1 of the present invention;

[0032] Figure 2 Photograph of the water contact angle provided for Comparative Example 3 of the present invention. Detailed Implementation

[0033] The technical solutions of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings. The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary, and should not be construed as limiting the implementation methods or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0034] The hydrophobic modified nano silica used in this invention was purchased from Nanjing Tianxing New Materials Co., Ltd., and its model number is TSP-L12.

[0035] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone any further purification treatment.

[0036] Example 1

[0037] This embodiment provides a self-cleaning coating for high-voltage transmission lines to prevent condensation and icing, and its preparation method, specifically including:

[0038] After the coating is cured on the surface of the conductor, it forms a base layer, an intermediate functional layer and a top layer stacked from the inside out.

[0039] The base coating is formed by applying a base coating to the surface of the wire and curing it. The base coating contains alkoxysilane, silica sol and tetraethoxysilane in a mass ratio of 1:4:1.

[0040] The intermediate functional layer uses siloxane elastomer as the continuous phase and includes phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, core-shell dielectric particles, and a low surface energy fluid phase. The core-shell dielectric particles are enriched in the interface region between the intermediate functional layer and the topcoat layer. The mass ratio of siloxane elastomer, phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, core-shell dielectric particles, and low surface energy fluid phase is 50:15:2:6:1:1.

[0041] The surface coating uses methyl vinyl silicone rubber as the continuous phase, contains micro / nano hierarchical rough components composed of hydrophobic modified nanoparticles and micron-sized inorganic particles, and contains polydimethylsiloxane. The mass ratio of methyl vinyl silicone rubber, hydrophobic modified nanoparticles, micron-sized inorganic particles and polydimethylsiloxane is 60:3:5:2.

[0042] The low surface energy fluid phase is fluorosilicone oil with a kinematic viscosity of 200 mmHg at 25°C. 2 / s;

[0043] The alkoxysilane in the base coating is γ-glycidyl ether propyltrimethoxysilane; the cured thickness of the base coating is 35 μm.

[0044] The intermediate functional layer of siloxane elastomer comprises vinyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, platinum-based catalyst, and 1-ethynyl-1-cyclohexanol, wherein the mass ratio of vinyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, platinum-based catalyst, and 1-ethynyl-1-cyclohexanol is 100:2:0.01:0.1; the cured thickness of the intermediate functional layer is 80 μm.

[0045] The phase change microcapsule is a double-shell structure microcapsule, comprising a phase change core material, an inorganic inner shell layer, and a siloxane outer shell layer; the siloxane outer shell layer contains vinyl groups; the phase change temperature of the phase change core material is +5℃;

[0046] The light-absorbing particles are manganese iron black pigment;

[0047] The insulating and thermally conductive filler is hexagonal boron nitride with a D50 of 35 μm; the insulating and thermally conductive filler is oriented in the intermediate functional layer, and the angle between the orientation direction and the coating thickness direction is ≤30°.

[0048] The core-shell dielectric particles have a barium titanate core / silicon dioxide shell structure, and the D50 of the core-shell dielectric particles is 500 nm; the interface region is the region 0-30 μm away from the interface between the intermediate functional layer and the topcoat layer, and the volume fraction of the core-shell dielectric particles in the interface region is 6 times that of the rest of the intermediate functional layer.

[0049] The hydrophobic modified nanoparticles in the surface coating are hydrophobic modified nano-silica, and the micron-sized inorganic particles are silica.

[0050] The core-shell dielectric particles form a continuous enrichment band in the interface region. The cured thickness of the enrichment band is 2 μm, and the mass fraction of the core-shell dielectric particles in the enrichment band is 10 times that of the mass fraction of the core-shell dielectric particles in the intermediate functional layer cured product.

[0051] Preparation methods include:

[0052] S1. Surface pretreatment of conductors: After degreasing by solvent wiping, clean with 3% sodium hydroxide aqueous solution at 55℃ for 5 minutes, rinse with deionized water until neutral, and dry with hot air at 90℃ for 16 minutes.

[0053] S2. Mechanical roughening: Alumina sand with 110 mesh is used for sandblasting, with a sandblasting pressure of 0.30MPa, a nozzle distance of 200mm, and a sandblasting time of 55s, so that the surface roughness Ra of the conductor is 3.0μm.

[0054] S3. Primer application and curing: Apply the primer coating to a curing thickness of 35μm, level at room temperature for 5 minutes, and then cure at 120℃ for 25 minutes to form the primer layer;

[0055] S4. Application and Orientation of Intermediate Functional Layer: Phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, and core-shell dielectric particles are dispersed in a siloxane system and applied to form an intermediate functional layer, which is cured to a thickness of 80 μm. During the leveling stage of the intermediate functional layer, a wire is used as the inner electrode and a coaxially arranged grounded metal mesh tube is used as the outer electrode. An alternating electric field is applied with an electric field strength of 3.2 kV / mm, a frequency of 1 kHz, and an application time of 300 s.

[0056] S5. Pre-curing: Pre-cur the intermediate functional layer at 52℃ for 30 minutes;

[0057] S6. Apply interface transition slurry: Apply interface transition slurry within 10 minutes after pre-curing to form an enrichment zone. The interface transition slurry contains core-shell dielectric particles, and the mass fraction of core-shell dielectric particles in the enrichment zone curing product is 10 times that in the intermediate functional layer curing product. The enrichment zone curing thickness is 2 μm. Then cure at 95°C for 80 minutes.

[0058] S7. Topcoat application and curing: Apply the topcoat to a curing thickness of 20μm, level at room temperature for 30 minutes, and then cure at 100℃ for 75 minutes to form a self-cleaning coating for high-voltage transmission lines that prevents condensation and icing.

[0059] Figure 1 The image provided in this embodiment shows the water contact angle, which is 155°. The coating surface is a superhydrophobic surface.

[0060] Example 2

[0061] This embodiment provides a self-cleaning coating for high-voltage transmission lines to prevent condensation and icing, and its preparation method, specifically including:

[0062] After the coating is cured on the surface of the conductor, it forms a base layer, an intermediate functional layer and a top layer stacked from the inside out.

[0063] The base coating is formed by applying a base coating to the surface of the wire and then curing it. The base coating contains alkoxysilane, silica sol and tetraethoxysilane in a mass ratio of 3:8:3.

[0064] The intermediate functional layer uses siloxane elastomer as the continuous phase and includes phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, core-shell dielectric particles, and a low surface energy fluid phase. The core-shell dielectric particles are enriched and distributed in the interface region between the intermediate functional layer and the topcoat layer. The mass ratio of siloxane elastomer, phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, core-shell dielectric particles, and low surface energy fluid phase is 70:25:6:12:3:5.

[0065] The surface coating uses methyl vinyl silicone rubber as the continuous phase, contains micro / nano-level rough components composed of hydrophobic modified nanoparticles and micron-sized inorganic particles, and contains polydimethylsiloxane. The mass ratio of methyl vinyl silicone rubber, hydrophobic modified nanoparticles, micron-sized inorganic particles and polydimethylsiloxane is 80:10:12:8.

[0066] The low surface energy fluid phase is silicone oil, with a kinematic viscosity of 1000 mmHg at 25°C. 2 / s;

[0067] The alkoxysilane in the base coating is vinyltriethoxysilane; the cured thickness of the base coating is 50 μm.

[0068] The intermediate functional layer of siloxane elastomer comprises vinyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, platinum-based catalyst, and 1-ethynyl-1-cyclohexanol, wherein the mass ratio of vinyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, platinum-based catalyst, and 1-ethynyl-1-cyclohexanol is 100:10:0.05:1; the cured thickness of the intermediate functional layer is 170 μm.

[0069] The phase change microcapsule is a double-shell structure microcapsule, comprising a phase change core material, an inorganic inner shell layer, and a siloxane outer shell layer; the siloxane outer shell layer contains hydrogen-containing silicon groups; the phase change temperature of the phase change core material is +2℃;

[0070] The light-absorbing particles are manganese iron black pigment;

[0071] The insulating and thermally conductive filler is aluminum nitride with a D50 of 60 μm; the insulating and thermally conductive filler is oriented in the intermediate functional layer, and the angle between the orientation direction and the coating thickness direction is ≤30°.

[0072] The core-shell dielectric particles have a titanium dioxide core / siloxane insulating shell structure, and the D50 of the core-shell dielectric particles is 300 nm; the interface region is the region 0-30 μm away from the interface between the intermediate functional layer and the topcoat layer, and the volume fraction of the core-shell dielectric particles in the interface region is 10 times that of the rest of the intermediate functional layer.

[0073] The hydrophobic modified nanoparticles in the surface coating are hydrophobic modified nano-silica, and the micron-sized inorganic particles are aluminum oxide;

[0074] The core-shell dielectric particles form a continuous enrichment band in the interface region, the cured thickness of the enrichment band is 6 μm, and the mass fraction of the core-shell dielectric particles in the enrichment band is 7 times the mass fraction of the core-shell dielectric particles in the intermediate functional layer cured product.

[0075] Preparation methods include:

[0076] S1. Surface pretreatment of conductors: After degreasing by solvent wiping, clean with 2% sodium hydroxide aqueous solution at 60℃ for 8 minutes, rinse with deionized water until neutral, and dry with hot air at 82℃ for 10 minutes.

[0077] S2. Mechanical roughening: Alumina sand with a mesh size of 120 is used for sandblasting, with a sandblasting pressure of 0.38MPa, a nozzle distance of 170mm, and a sandblasting time of 30s, so that the surface roughness Ra of the conductor is 4.0μm.

[0078] S3. Primer application and curing: Apply the primer coating to a curing thickness of 50μm, level at room temperature for 9 minutes, and then cure at 105℃ for 10 minutes to form the primer layer;

[0079] S4. Application and Orientation of Intermediate Functional Layer: Phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, and core-shell dielectric particles are dispersed in a siloxane system and applied to form an intermediate functional layer with a cured thickness of 170 μm. During the leveling stage of the intermediate functional layer, a wire is used as the inner electrode, and a grounded metal mesh tube is coaxially arranged as the outer electrode. An alternating electric field is applied with a field strength of 4.0 kV / mm, a frequency of 6 kHz, and an application time of 220 s.

[0080] S5. Pre-curing: Pre-cur the intermediate functional layer at 40℃ for 40 minutes;

[0081] S6. Apply interface transition slurry: Apply interface transition slurry within 7 minutes after pre-curing to form an enrichment zone. The interface transition slurry contains core-shell dielectric particles, and the mass fraction of core-shell dielectric particles in the enrichment zone curing product is 7 times the mass fraction of core-shell dielectric particles in the intermediate functional layer curing product. The enrichment zone curing thickness is 6 μm. Then cure at 80℃ for 120 minutes.

[0082] S7. Topcoat application and curing: Apply the topcoat to a curing thickness of 60μm, level at room temperature for 22 minutes, and then cure at 80℃ for 120 minutes to form a self-cleaning coating for high-voltage transmission lines that prevents condensation and icing.

[0083] Example 3

[0084] This embodiment provides a self-cleaning coating for high-voltage transmission lines to prevent condensation and icing, and its preparation method, specifically including:

[0085] After the coating cures on the surface of the conductor, it forms a base layer, an intermediate functional layer, and a top layer stacked sequentially from the inside out:

[0086] The base coating is formed by applying a base coating to the surface of the wire and then curing it. The base coating contains alkoxysilane, silica sol and tetraethoxysilane in a mass ratio of 2:5:2.

[0087] The intermediate functional layer uses siloxane elastomer as the continuous phase and includes phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, core-shell dielectric particles, and a low surface energy fluid phase. The core-shell dielectric particles are enriched in the interface region between the intermediate functional layer and the topcoat layer. The mass ratio of siloxane elastomer, phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, core-shell dielectric particles, and low surface energy fluid phase is 55:18:3:8:2:2.

[0088] The surface coating uses methyl vinyl silicone rubber as the continuous phase, contains micro / nano-level rough components composed of hydrophobic modified nanoparticles and micron-sized inorganic particles, and contains polydimethylsiloxane. The mass ratio of methyl vinyl silicone rubber, hydrophobic modified nanoparticles, micron-sized inorganic particles and polydimethylsiloxane is 67:5:8:4.

[0089] The low surface energy fluid phase is fluorosilicone oil with a kinematic viscosity of 400 mmHg at 25°C. 2 / s; The low surface energy migration component is a fluorosiloxane oligomer with a number average molecular weight of 12000;

[0090] The alkoxysilane in the base coating is aminopropyltriethoxysilane; the cured thickness of the base coating is 18 μm.

[0091] The addition-crosslinked siloxane elastomer of the intermediate functional layer comprises vinyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, platinum-based catalyst, and 1-ethynyl-1-cyclohexanol, wherein the mass ratio of vinyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, platinum-based catalyst, and 1-ethynyl-1-cyclohexanol is 100:4:0.03:0.4; the cured thickness of the intermediate functional layer is 400 μm.

[0092] The phase change microcapsule is a double-shell structure microcapsule, comprising a phase change core material, an inorganic inner shell layer, and a siloxane outer shell layer; the siloxane outer shell layer contains vinyl groups and hydrogen-containing silicon groups; the phase change temperature of the phase change core material is -5℃;

[0093] The light-absorbing particles are manganese iron black pigment;

[0094] The insulating and thermally conductive filler is hexagonal boron nitride with a D50 of 12μm; the insulating and thermally conductive filler is oriented in the intermediate functional layer, and the angle between the orientation direction and the coating thickness direction is ≤30°.

[0095] The core-shell dielectric particles have a zinc oxide core / silicon dioxide shell structure, and the D50 of the core-shell dielectric particles is 50nm; the interface region is the region 0-30μm away from the interface between the intermediate functional layer and the topcoat layer, and the volume fraction of the core-shell dielectric particles in the interface region is 3 times that of the rest of the intermediate functional layer.

[0096] The hydrophobic modified nanoparticles in the surface coating are hydrophobic modified nano-silica, and the micron-sized inorganic particles are boron nitride.

[0097] The core-shell dielectric particles form a continuous enrichment band in the interface region, the cured thickness of the enrichment band is 20 μm, and the mass fraction of the core-shell dielectric particles in the enrichment band is twice the mass fraction of the core-shell dielectric particles in the intermediate functional layer cured product.

[0098] Preparation methods include:

[0099] S1. Surface pretreatment of conductors: After degreasing by solvent wiping, clean with 4% sodium hydroxide aqueous solution at 46℃ for 15 min, rinse with deionized water until neutral, and dry with hot air at 60℃ for 24 min.

[0100] S2. Mechanical roughening: Alumina sand with a mesh size of 95 is used for sandblasting, with a sandblasting pressure of 0.60MPa, a nozzle distance of 100mm, and a sandblasting time of 90s, so that the surface roughness Ra of the conductor is 1.8μm.

[0101] S3. Primer application and curing: Apply the primer coating to a curing thickness of 18μm, level at room temperature for 20 minutes, and then cure at 60℃ for 45 minutes to form the primer layer.

[0102] S4. Application and Orientation of Intermediate Functional Layer: Phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, and core-shell dielectric particles are dispersed in a siloxane system and applied to form an intermediate functional layer, which is cured to a thickness of 400 μm. During the leveling stage of the intermediate functional layer, a wire is used as the inner electrode and a coaxially arranged grounded metal mesh tube is used as the outer electrode. An alternating electric field is applied with an electric field strength of 2.0 kV / mm, a frequency of 20 kHz, and an application time of 60 s.

[0103] S5. Pre-curing: Pre-cur the intermediate functional layer at 70℃ for 18 minutes;

[0104] S6. Apply interface transition slurry: Apply interface transition slurry within 1 minute after pre-curing to form an enrichment zone. The interface transition slurry contains core-shell dielectric particles, and the mass fraction of core-shell dielectric particles in the enrichment zone curing product is twice the mass fraction of core-shell dielectric particles in the intermediate functional layer curing product. The curing thickness of the enrichment zone is 20 μm. Then cure at 120℃ for 35 minutes.

[0105] S7. Topcoat application and curing: Apply the topcoat to a curing thickness of 150μm. After leveling at room temperature for 5 minutes, cure at 125℃ for 40 minutes to form a self-cleaning coating for high-voltage transmission lines that prevents condensation and icing.

[0106] Example 4

[0107] This embodiment provides a self-cleaning coating for high-voltage transmission lines to prevent condensation and icing, and its preparation method, specifically including:

[0108] After the coating is cured on the surface of the conductor, it forms a base layer, an intermediate functional layer and a top layer stacked from the inside out.

[0109] The base coating is formed by applying a base coating to the surface of the wire and then curing it. The base coating contains alkoxysilane, silica sol and tetraethoxysilane in a mass ratio of 3:7:2.

[0110] The intermediate functional layer uses siloxane elastomer as the continuous phase and includes phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, core-shell dielectric particles, and a low surface energy fluid phase. The core-shell dielectric particles are enriched in the interface region between the intermediate functional layer and the topcoat layer. The mass ratio of siloxane elastomer, phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, core-shell dielectric particles, and low surface energy fluid phase is 66:23:5:10:2:4.

[0111] The surface coating uses methyl vinyl silicone rubber as the continuous phase, contains micro / nano hierarchical rough components composed of hydrophobic modified nanoparticles and micron-sized inorganic particles, and contains polydimethylsiloxane. The mass ratio of methyl vinyl silicone rubber, hydrophobic modified nanoparticles, micron-sized inorganic particles and polydimethylsiloxane is 73:7:12:6.

[0112] The low surface energy fluid phase is a mixture of silicone oil and fluorosilicone oil, with a kinematic viscosity of 700 mmHg at 25°C. 2 / s;

[0113] The alkoxysilane in the base coating is a combination of γ-glycidyl ether propyltrimethoxysilane and vinyltriethoxysilane; the cured thickness of the base coating is 5 μm.

[0114] The intermediate functional layer's siloxane elastomer comprises vinyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, a platinum-based catalyst, and 1-ethynyl-1-cyclohexanol, with a mass ratio of vinyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, platinum-based catalyst, and 1-ethynyl-1-cyclohexanol of 100:8:0.04:0.7; the cured thickness of the intermediate functional layer is 310 μm.

[0115] The phase change microcapsule is a double-shell structure microcapsule, comprising a phase change core material, an inorganic inner shell layer, and a siloxane outer shell layer; the siloxane outer shell layer contains vinyl groups; the phase change temperature of the phase change core material is -2℃;

[0116] The light-absorbing particles are manganese iron black pigment;

[0117] The insulating and thermally conductive filler is aluminum nitride with a D50 of 1 μm; the insulating and thermally conductive filler is oriented in the intermediate functional layer, and the angle between the orientation direction and the coating thickness direction is ≤30°.

[0118] The core-shell dielectric particles have a strontium titanate core / siloxane insulating shell structure, and the D50 of the core-shell dielectric particles is 120 nm; the interface region is the region 0-30 μm away from the interface between the intermediate functional layer and the topcoat layer, and the volume fraction of the core-shell dielectric particles in the interface region is 1.5 times that of the rest of the intermediate functional layer.

[0119] The hydrophobic modified nanoparticles in the surface coating are hydrophobic modified nano-silica, and the micron-sized inorganic particles are a combination of silicon dioxide and boron nitride.

[0120] The core-shell dielectric particles form a continuous enrichment band in the interface region, the cured thickness of the enrichment band is 14 μm, and the mass fraction of the core-shell dielectric particles in the enrichment band is 4 times the mass fraction of the core-shell dielectric particles in the intermediate functional layer cured product.

[0121] Preparation methods include:

[0122] S1. Surface pretreatment of conductors: After degreasing by solvent wiping, clean with 5% sodium hydroxide aqueous solution at 40℃ for 12 min, rinse with deionized water until neutral, and dry with hot air at 70℃ for 30 min.

[0123] S2. Mechanical roughening: Alumina sand with 80 mesh is used for sandblasting, with a sandblasting pressure of 0.50MPa, a nozzle distance of 130mm, and a sandblasting time of 120s, so that the surface roughness Ra of the conductor is 1.0μm.

[0124] S3. Primer application and curing: Apply the primer coating to a curing thickness of 5μm, level at room temperature for 15 minutes, and then cure at 80℃ for 60 minutes to form the primer layer;

[0125] S4. Application and Orientation of Intermediate Functional Layer: Phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, and core-shell dielectric particles are dispersed in an addition-crosslinked siloxane system and applied to form an intermediate functional layer with a cured thickness of 310 μm. During the leveling stage of the intermediate functional layer, a wire is used as the inner electrode, and a grounded metal mesh tube is coaxially arranged as the outer electrode. An alternating electric field is applied with a field strength of 1.0 kV / mm, a frequency of 14 kHz, and an application time of 120 s.

[0126] S5. Pre-curing: Pre-cur the intermediate functional layer at 80℃ for 10 minutes;

[0127] S6. Apply interface transition slurry: Apply interface transition slurry within 3 minutes after pre-curing to form an enrichment zone. The interface transition slurry contains core-shell dielectric particles, and the mass fraction of core-shell dielectric particles in the enrichment zone curing product is 4 times the mass fraction of core-shell dielectric particles in the intermediate functional layer curing product. The curing thickness of the enrichment zone is 14 μm. Then cure at 140℃ for 10 minutes.

[0128] S7. Topcoat application and curing: Apply the topcoat to achieve a curing thickness of 110μm. After leveling at room temperature for 12 minutes, cure at 140℃ for 10 minutes to form a self-cleaning coating for high-voltage transmission lines that prevents condensation and icing.

[0129] Comparative Example 1

[0130] This comparative example provides a self-cleaning coating for high-voltage transmission lines to prevent condensation and icing, and its preparation method. The difference between this and Example 1 is that S6 is omitted, and no interface transition slurry is applied to form a core-shell dielectric particle enrichment band. The core-shell dielectric particles are only added according to the intermediate functional layer formula and are uniformly dispersed in the intermediate functional layer, without forming an interface region enrichment distribution. Other process parameters and operating conditions are exactly the same as in Example 1.

[0131] Comparative Example 2

[0132] This comparative example provides a self-cleaning coating for high-voltage transmission lines to prevent condensation and icing, and its preparation method. The difference between this and Example 1 is that in S4, after the intermediate functional layer is applied, no AC electric field is applied during the leveling stage, and the insulating and thermally conductive filler is dispersed only by conventional stirring and leveling shearing without orientation control. Other process parameters and operating conditions are exactly the same as in Example 1.

[0133] Comparative Example 3

[0134] This comparative example provides a self-cleaning coating for high-voltage transmission lines to prevent condensation and icing, and its preparation method. The difference between this and Example 1 is that no low surface energy fluid phase is added to the intermediate functional layer, and no low surface energy migration component is added to the top coating. Instead, equal masses of vinyl-terminated polydimethylsiloxane are used to replace them. Other process parameters and operating conditions are exactly the same as in Example 1. Figure 2 The water contact angle photograph provided for this comparative example has a contact angle of 135°, which is smaller than that of Example 1.

[0135] Performance testing: The test object is a high-voltage transmission line conductor section that has been coated and fully cured. At least 3 independent samples are taken for each test and the average value is taken.

[0136] Ice adhesion strength was determined by the shear push-off method: an ice sleeve of a specified length was prepared in the middle of the conductor under low temperature conditions, frozen until completely frozen and kept at thermal equilibrium, and then the ice sleeve was pushed off along the conductor axis using a universal testing machine. The maximum push-off force was recorded and converted into ice adhesion strength (kPa) according to the contact area between the ice and the outer surface of the conductor.

[0137] The delayed freezing time was determined at -10℃ and 85%RH: the initial time was recorded when the sample reached thermal equilibrium, and the freezing time was recorded when a stable and continuously growing frost / ice phase first appeared on the surface and did not dissipate within the specified observation time. The time difference between the two was the delayed freezing time.

[0138] Self-de-icing efficiency was assessed using the light-induced de-icing mass method: Standard ice was prepared under identical environmental conditions, and its mass m0 was measured. A solar simulator was then used at a speed of 0.5 kW / m². 2 Irradiation was applied for a fixed duration t, and the residual icing mass m was measured. t Self-de-icing efficiency η=(m0−m t ) / m0×100%.

[0139] The anti-condensation voltage is determined by power frequency boosting under condensation conditions and partial discharge criteria: with coated wire as the inner electrode and coaxial grounded metal mesh cylinder as the outer electrode, after a continuous condensation water film is formed in the temperature and humidity chamber, the voltage is boosted at a fixed boosting rate, and the voltage at which a stable and repeatable partial discharge occurs and exceeds a preset threshold is recorded as the anti-condensation voltage, and expressed in the form of ×U0.

[0140] The fluorescent ultraviolet lamp artificial climate aging test was conducted according to GB / T 14522-2008. After the cumulative aging time reached 3000h, the sample was taken out, the surface was gently rinsed with deionized water and dried, and then placed in a standard environment (about 23℃, 50%RH) for no less than 24h before appearance rating. The degree of chalking was evaluated according to GB / T 1766-2008. The coating surface was sampled using the adhesive tape method, and the chalking grade was given by comparing it with the chalking rating spectrum under diffuse light. The judgment rule was: chalking grade ≤1 is qualified; chalking grade >1 is unqualified.

[0141] The test results are shown in Table 1.

[0142] Table 1. Test results of anti-condensation and anti-icing self-cleaning coatings for high-voltage transmission lines in Examples 1-4 and Comparative Examples 1-3.

[0143]

[0144] As shown in Table 1, compared with Example 1, Comparative Example 1 showed increased ice adhesion strength, increased delayed icing time, decreased self-de-icing efficiency, decreased anti-condensation voltage, and failed artificial climate aging; Comparative Example 2 showed increased ice adhesion strength, decreased delayed icing time, decreased self-de-icing efficiency, decreased anti-condensation voltage, and passed artificial climate aging; Comparative Example 3 showed increased ice adhesion strength, decreased delayed icing time, decreased self-de-icing efficiency, decreased anti-condensation voltage, and failed artificial climate aging.

[0145] This is because, in Comparative Example 1, after the enrichment zone was removed, the interfacial dielectric constant and electric field shaping were insufficient. The electric field at the three-phase line of the condensate film was more easily concentrated, triggering partial discharge prematurely. Electro-erosion caused a decrease in the anti-condensation voltage. During the weathering aging process, the discharge products and contaminant deposition accelerated surface deterioration and pulverization. Increased surface wetting and adhesion led to increased ice adhesion, affecting self-de-icing. In Comparative Example 2, without an applied AC electric field, the insulating thermally conductive filler was randomly oriented, making it difficult to establish a thermally conductive network in the thickness direction. Photothermal and phase change exothermic reactions were difficult to transport quickly to the ice-coating interface, resulting in insufficient interfacial liquid film formation, which shortened the delayed icing period and reduced self-de-icing efficiency. After removing the low surface energy fluid phase and migrating components in Comparative Example 4, the surface lacks a sustainable low surface energy supply and lubricating film mechanism, making it easier for condensation to spread into a continuous water film and promote nucleation, thus delaying and shortening the freezing period. Increased friction at the ice-coating interface leads to increased ice adhesion and decreased self-de-icing efficiency. After weathering and aging, it is more prone to dirt accumulation and micro-cracks and powdering. At the same time, the increased conductivity of the water film further reduces the anti-condensation voltage.

[0146] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A self-cleaning coating for high-voltage transmission lines to prevent condensation and icing, characterized in that, The coating comprises a base layer, an intermediate functional layer, and a top layer, which are stacked sequentially from the inside out after being cured on the surface of the conductor. The base coating is formed by applying a base coating to the surface of the wire and then curing it. The base coating contains alkoxysilane, silica sol and tetraethoxysilane. The intermediate functional layer uses siloxane elastomer as a continuous phase and includes phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, core-shell dielectric particles, and a low surface energy fluid phase. The low surface energy fluid phase is silicone oil and / or fluorosilicone oil, wherein the core-shell dielectric particles are enriched and distributed in the interface region between the intermediate functional layer and the surface coating layer. The surface coating uses methyl vinyl silicone rubber as the continuous phase, contains micro / nano-level rough components composed of hydrophobic modified nanoparticles and micron-sized inorganic particles, and contains polydimethylsiloxane. The insulating and thermally conductive filler is selected from hexagonal boron nitride and / or aluminum nitride, with a D50 of 1-60μm; the insulating and thermally conductive filler is oriented in the intermediate functional layer, and the angle between the orientation direction and the coating thickness direction is ≤30°.

2. The self-cleaning coating for high-voltage transmission lines against condensation and icing according to claim 1, characterized in that, The alkoxysilane in the base coating is selected from one or more of γ-glycidyl ether propyltrimethoxysilane, vinyltriethoxysilane, and aminopropyltriethoxysilane; the cured thickness of the base coating is 5-50 μm.

3. The self-cleaning coating for high-voltage transmission lines against condensation and icing according to claim 1, characterized in that, The siloxane elastomer of the intermediate functional layer comprises vinyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, platinum-based catalyst and 1-ethynyl-1-cyclohexanol; the cured thickness of the intermediate functional layer is 80-400 μm.

4. The self-cleaning coating for high-voltage transmission lines against condensation and icing according to claim 1, characterized in that, The phase change microcapsule is a double-shell structure microcapsule, comprising a phase change core material, an inorganic inner shell layer, and a siloxane outer shell layer; the siloxane outer shell layer contains vinyl groups and / or hydrosilane groups; the phase change temperature of the phase change core material is -5℃ to +5℃.

5. The self-cleaning coating for high-voltage transmission lines against condensation and icing according to claim 1, characterized in that, The light-absorbing particles are selected from black inorganic pigment particles.

6. The self-cleaning coating for high-voltage transmission lines against condensation and icing according to claim 1, characterized in that, The core of the core-shell dielectric particle is selected from one or more of barium titanate, strontium titanate, titanium dioxide, zinc oxide, and silicon carbide; the shell of the core-shell dielectric particle is an insulating shell layer of silicon dioxide and siloxane; the D50 of the core-shell dielectric particle is 50-500 nm; the interface region is the region 0-30 μm away from the interface between the intermediate functional layer and the topcoat layer, and the volume fraction of the core-shell dielectric particle in the interface region is 1.5-10 times that of the remaining regions of the intermediate functional layer.

7. The self-cleaning coating for high-voltage transmission lines against condensation and icing according to claim 1, characterized in that, The hydrophobic modified nanoparticles in the surface coating are hydrophobic modified nano-silica, and the micron-sized inorganic particles are selected from one or more of silica, alumina, and boron nitride. The low surface energy fluid phase has a kinematic viscosity of 200-1000 mmHg at 25°C. 2 / s.

8. The self-cleaning coating for high-voltage transmission lines against condensation and icing according to claim 1, characterized in that, The core-shell dielectric particles form a continuous enrichment band in the interface region. The cured thickness of the enrichment band is 2-20 μm, and the mass fraction of the core-shell dielectric particles in the enrichment band is 2-10 times that of the core-shell dielectric particles in the cured intermediate functional layer.

9. A method for preparing a self-cleaning coating for high-voltage transmission lines as described in any one of claims 1-8, characterized in that, Preparation methods include: S1. After cleaning the wires with solvent to remove oil, clean them with a 2-5% alkaline cleaning solution at 40-60℃ for 5-15 minutes, rinse with deionized water until neutral, and dry with hot air at 60-90℃ for 10-30 minutes. S2. Use 80-120 mesh alumina sand for sandblasting, with a sandblasting pressure of 0.30-0.60MPa, a nozzle distance of 100-200mm, and a sandblasting time of 30-120s to make the surface roughness Ra of the conductor 1.0-4.0μm. S3. Apply the primer coating and let it cure to a thickness of 5-50μm. After leveling at room temperature for 5-20 minutes, cure at 60-120℃ for 10-60 minutes to form the primer coating. S4. Phase change microcapsules, light-absorbing particles, insulating and thermally conductive fillers, and core-shell dielectric particles are dispersed in an addition-crosslinked siloxane system and coated to form an intermediate functional layer, which is cured to a thickness of 80-400 μm. During the leveling stage of the intermediate functional layer, a wire is used as the inner electrode and a grounded metal mesh tube is coaxially arranged as the outer electrode. An alternating electric field is applied with an electric field strength of 1.0-4.0 kV / mm, a frequency of 1-20 kHz, and an application time of 60-300 s. S5. Pre-cur the intermediate functional layer at 40-80℃ for 10-40 minutes; S6. Apply an interface transition slurry to form an enrichment zone within 1-10 minutes after pre-curing. The interface transition slurry contains core-shell dielectric particles. Then cure at 80-140℃ for 10-120 minutes. S7. Apply the topcoat to cure to a thickness of 20-150μm. After leveling at room temperature for 5-30 minutes, cure at 80-140℃ for 10-120 minutes to form a self-cleaning coating for high-voltage transmission lines that prevents condensation and icing.

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