A high-voltage cable joint flame-out and explosion venting composite material, a preparation method and device

Abstract

The embodiment of the application provides a high-voltage cable joint flame-out and explosion relief composite material, a preparation method and a device, and relates to the technical field of high-voltage cable protection. The composite material comprises: an intelligent liquid sealing layer; the intelligent liquid sealing layer is composed of a plurality of microcapsules with a core-shell structure; the microcapsules comprise a hydrophilic core, a hydrophobic shell and an interface layer; the hydrophobic shell is wrapped around the periphery of the hydrophilic core, and the interface layer is located between the hydrophilic core and the hydrophobic shell; the main component of the hydrophilic core is deionized water; the main component of the hydrophobic shell is perfluoropolyether oil; and the interface layer is a fluorocarbon surfactant. The high-voltage cable joint flame-out and explosion relief composite material of the application forms an efficient flame-out mechanism of physical cooling and asphyxiation isolation based on the instantaneous rupture of microcapsules under explosion overpressure triggering and the synergistic effect of multiple components.

Description

Technical Field

[0001] This invention relates to the field of high-voltage cable protection technology, and in particular to a flame-extinguishing and explosion-proof composite material for high-voltage cable joints, its preparation method, and apparatus. Background Technology

[0002] High-voltage cable joints, as key connecting components in power transmission and distribution systems, play a crucial role in the efficient and safe transmission of electrical energy. Their operational reliability directly affects the stability and security of the entire power grid. However, in actual operation, due to factors such as manufacturing defects, installation process deviations, long-term electro-thermal-mechanical stress aging, or short-term overload, partial discharge phenomena can easily occur inside cable joints. If not suppressed in time, partial discharge can rapidly develop into arc breakdown, triggering pyrolysis, carbonization, and even violent deflagration of the cable insulation material. This fault process typically completes within milliseconds, accompanied by temperatures reaching thousands of degrees Celsius and instantaneous overpressures of tens of atmospheres. This not only causes pulverizing damage to traditional joint structures but also easily ignites surrounding combustibles, resulting in large-scale power outages, damage to major equipment, and even endangering personal safety, leading to severe economic losses and social impact.

[0003] To address the aforementioned risks, existing technologies generally incorporate explosion vents in the explosion-proof housings of cable joints to release internal overpressure and prevent explosions. However, such passive pressure relief structures only mitigate mechanical damage and cannot prevent high-temperature, high-pressure flames and flammable gases from erupting through the vents, potentially triggering secondary fires or arc reignition, thus presenting a significant safety shortcoming. While some solutions attempt to integrate fire extinguishing devices into the explosion venting path, these often rely on electronic sensors, actuators, and external power supply systems, resulting in issues such as response delays, complex structures, low reliability, and high maintenance costs. These solutions fail to meet the high reliability, maintenance-free operation, and rapid response safety requirements of high-voltage power equipment.

[0004] In recent years, microencapsulated smart response materials have shown application potential in the field of fire protection and safety engineering. However, existing microencapsulation technology is mostly used in static matrices such as coatings, textiles or flame-retardant plastics, and has not yet been applied to high-voltage electrical equipment, especially in application scenarios such as high-voltage cable joints where space is limited, insulation requirements are stringent, and response time is extremely short. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention provides a flame extinguishing and explosion relief device for high-voltage cable joints. The technical solution is as follows:

[0006] This invention provides a flame-quenching and explosion-proof composite material for high-voltage cable joints, comprising: an intelligent liquid sealing layer; the intelligent liquid sealing layer is composed of multiple core-shell microcapsules; each microcapsule includes a hydrophilic core, a hydrophobic shell, and an interface layer; the hydrophobic shell covers the periphery of the hydrophilic core, and the interface layer is located between the hydrophilic core and the hydrophobic shell; the main component of the hydrophilic core is deionized water; the main component of the hydrophobic shell is perfluoropolyether oil; and the interface layer is a fluorocarbon surfactant.

[0007] Optionally, the hydrophilic core further comprises an antifreeze agent and an insulating reinforcing agent; the antifreeze agent is selected from one or more of glycerol, ethylene glycol, propylene glycol, glycerol, and dimethyl sulfoxide; the insulating reinforcing agent is selected from one or more of ammonium borate, ammonium dihydrogen phosphate, sodium tetraborate, and triethanolamine; the amount of antifreeze agent added is 10%-15% of the mass of deionized water, and the amount of insulating reinforcing agent added is 5%-8% of the mass of deionized water.

[0008] Optionally, the perfluoropolyether oil has a molecular weight of 2000-3000, a kinematic viscosity of 80-120 cSt at 25°C, and a dielectric strength ≥40kV / 2.5mm.

[0009] Optionally, the fluorocarbon surfactant is selected from one or more of perfluorobutane sulfonate, perfluorooctyl polyoxyethylene ether, difluoroalkyl phosphate, fluorosulfonamide acrylate, perfluorohexyl ethyl phosphate, perfluorobutyl ethyl polyoxypropylene ether, and perfluoroalkyl betaine.

[0010] Optionally, it further includes: a main liquid protective medium layer; the main liquid protective medium layer is located below the intelligent liquid sealing layer described above;

[0011] The main liquid protective medium layer includes a base liquid; the base liquid, by mass percentage, includes: 60%-70% synthetic ester, 20%-30% modified silicone oil, and 10%-15% perfluoropolyether oil.

[0012] Optionally, the main liquid protective medium layer further includes functional additives; the functional additives include nano-SiO2 particles, nano-Al2O3 particles and flame retardants; the amount of nano-SiO2 particles added is 3%-5% of the mass of the base liquid; the amount of nano-Al2O3 particles added is 2%-3% of the mass of the base liquid; and the amount of flame retardant added is 5%-8% of the mass of the base liquid.

[0013] This invention also provides a method for preparing the flame-quenching and explosion-proof composite material for high-voltage cable joints as described above, characterized by comprising the following steps:

[0014] S11: Add a fluorocarbon surfactant to the perfluoropolyether oil and stir until completely dissolved to form a homogeneous oil phase;

[0015] S12: Deionized water is continuously added to the stirred oil phase through a conduit with an inner diameter ≤1 mm to form a W / O type emulsion;

[0016] S13: Pour the W / O type emulsion into the polyvinyl alcohol aqueous solution and stir to form a W / O / W type double emulsion;

[0017] S14: Surface curing of W / O / W type dual emulsion yields core-shell structured microcapsules, and several microcapsules are stacked to form an intelligent liquid sealing layer.

[0018] The present invention also provides a high-voltage cable joint flame extinguishing and explosion relief device, which includes: an explosion-proof housing, an explosion relief port mechanism, and the aforementioned high-voltage cable joint flame extinguishing and explosion relief composite material;

[0019] The explosion-proof housing has an inner cavity; the explosion-proof housing has cable sealing interfaces communicating with the inner cavity at both ends along its axis; the main liquid protective medium layer fills the inner cavity of the explosion-proof housing and is used to immerse the high-voltage cable joint located in the inner cavity;

[0020] The explosion relief mechanism includes a pressure relief channel and an explosion relief cover plate; the pressure relief channel is disposed on the explosion-proof housing and communicates with the inner cavity; the explosion relief cover plate is used to cover and seal the pressure relief channel; an annular chamber is provided inside the pressure relief channel; the intelligent liquid sealing layer is disposed inside the annular chamber.

[0021] Optionally, the explosion vent mechanism further includes an elastic reset member; one end of the explosion vent cover is rotatably connected to one side of the pressure relief channel via a hinge structure, and the other end of the explosion vent cover is elastically connected to the other side of the pressure relief channel via the elastic reset member.

[0022] Optionally, the cable sealing interface of the explosion-proof housing is provided with an annular sealing structure, the annular sealing structure including an elastic sealing ring and a flame-retardant and waterproof layer disposed outside the elastic sealing ring.

[0023] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0024] (1) The intelligent liquid sealing layer of the present invention is based on the instantaneous rupture of microcapsules triggered by explosive overpressure and the synergistic effect of multiple components to form a highly efficient flame extinguishing mechanism of physical cooling and suffocation isolation. Under normal conditions, the hydrophobic shell composed of perfluoropolyether oil completely covers the hydrophilic core mainly composed of high-purity deionized water, and the microcapsule structure is maintained by the interfacial film formed by fluorocarbon surfactants. When a deflagration fault occurs inside the cable joint, generating millisecond-level shock waves and overpressure, the microcapsules rupture rapidly under the action of external shear and pressure change, releasing the internal functional components. The high-purity deionized water vaporizes violently due to its extremely high latent heat of vaporization, absorbing a large amount of heat from the fireball and high-temperature gas, achieving rapid cooling and effectively interrupting the combustion chain reaction. At the same time, the released perfluoropolyether oil, because its density is greater than that of air and it is itself non-flammable, forms a fine, settling non-flammable oil film in the flame area, covering the surface of the burning material, isolating oxygen, and achieving physical suffocation fire extinguishing.

[0025] (2) The main liquid protective medium layer of the present invention uses synthetic ester as the main continuous phase, modified silicone oil as the performance adjustment phase, and a small amount of perfluoropolyether oil as the high-performance reinforcing phase. The three form a homogeneous and stable system with high flash point, low pour point, high thermal conductivity, high volume resistivity and excellent anti-aging ability through molecular polarity matching, interface compatibility and functional complementarity. When facing the complex environment in the early stage of explosion, it can play multiple protective functions such as heat absorption vaporization cooling and chemical flame retardant inhibition, build the first active protection barrier, and automatically fill the burning defects through the residual liquid film after the fault, realizing partial self-recovery of insulation performance.

[0026] (3) The high-voltage cable joint flame extinguishing and explosion relief device provided by the present invention includes an explosion-proof shell, a main liquid protective medium layer, an intelligent liquid sealing layer, and an explosion relief port mechanism, which together constitute a triple collaborative protection system integrating energy absorption, active fire extinguishing and pressure relief, and environmental self-recovery. When an arc explosion occurs in the high-voltage cable joint, the main liquid protective medium suppresses the temperature rise by vaporizing and absorbing heat. As the internal pressure rises rapidly to the set threshold, the explosion relief port mechanism opens instantly, simultaneously triggering the rupture and atomization of the core-shell structure microcapsules in the intelligent liquid sealing layer. Its hydrophilic core vaporizes violently to achieve efficient cooling, while the hydrophobic shell spreads out as a non-flammable liquid curtain to isolate oxygen, transforming the traditional pressure relief channel into an active fire extinguishing outlet that "extinguishes as soon as it is released". Subsequently, the elastic reset component drives the explosion relief cover to close automatically, rebuilding the sealed environment. Combined with the internal oxygen consumption state and the residual highly insulating liquid components, it quickly constructs low-oxygen asphyxiation and insulation recovery conditions. The main liquid medium restores its fluidity after cooling, collaboratively repairing the membrane filling ablation defects and realizing the self-repair function. The device of this invention integrates energy absorption, active fire suppression and pressure relief, and environmental self-recovery through triple deep collaborative protection, forming a closed-loop intervention throughout the entire process. Its response relies entirely on physical and chemical mechanisms, requiring no external energy or control signals, and can be autonomously activated within milliseconds, significantly reducing operation and maintenance costs and power outage time, and greatly improving the safety resilience and power supply reliability of the power system. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the structure of a high-voltage cable joint flame extinguishing and explosion relief device according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram showing the disassembled structure of a high-voltage cable joint flame extinguishing and explosion relief device according to an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of an intelligent liquid sealing layer structure provided in an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of a vent mechanism provided in an embodiment of the present invention.

[0032] Figure label:

[0033] 1-Explosion-proof housing; 2-Main liquid protective medium layer; 3-Intelligent liquid sealing layer; 4-Explosion relief port mechanism; 5-Cable sealing interface; 6-High-voltage cable connector; 11-Upper housing; 12-Lower housing; 13-Flange edge; 14-Connecting bolt; 31-Hydrophilic core; 32-Hydrophobic outer shell; 33-Annular chamber; 41-Connecting seat; 42-Sealing gasket; 43-Explosion relief cover plate; 44-Elastic reset element; 51-Elastic sealing ring; 52-Flame-retardant and waterproof layer. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising,” “including,” or “including,” and similar terms mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or “connected,” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0036] It should be noted that the terms "up", "down", "left", "right", "front" and "back" used in this invention are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0037] This invention provides a flame-quenching and explosion-proof composite material for high-voltage cable joints, comprising: an intelligent liquid sealing layer 3; the intelligent liquid sealing layer 3 is composed of multiple core-shell microcapsules; each microcapsule includes a hydrophilic core 31, a hydrophobic outer shell 32, and an interface layer; the hydrophobic outer shell 32 covers the periphery of the hydrophilic core 31, and the interface layer is located between the hydrophilic core 31 and the hydrophobic outer shell 32; the main component of the hydrophilic core 31 is deionized water; the main component of the hydrophobic outer shell 32 is perfluoropolyether oil; and the interface layer is a fluorocarbon surfactant. The particle size of the microcapsules is preferably 3-8 micrometers.

[0038] Perfluoropolyether oil, as the main material of the hydrophobic outer shell 32 of the microcapsule, preferably has a molecular weight of 2000-3000, a kinematic viscosity of 80-120 cSt at 25°C, and a dielectric strength ≥40kV / 2.5mm. This molecular weight and viscosity provide the shell with sufficient mechanical strength, enabling it to stably encapsulate the hydrophilic core 31 under normal operating conditions and maintain the integrity of the microcapsule structure. On the other hand, it avoids an overly dense or rigid shell, ensuring timely rupture under the instantaneous shock wave and shear force generated by an explosion, releasing the internal fire-extinguishing components. Simultaneously, this viscosity range is beneficial for forming uniformly sized and stably dispersed primary W / O type droplets during emulsification. Furthermore, the perfluoropolyether oil has excellent high dielectric strength, ensuring that the intelligent liquid sealing layer 3 maintains good electrical insulation performance during long-term service. Perfluoropolyether oil is non-flammable and chemically inert. It can not only form a non-flammable oil film to cover the burning area and isolate oxygen to achieve physical suffocation and extinguish fire during deflagration, but also remain compatible with the hydrophilic core 31 components during long-term storage and operation, ensuring the long-term stability and functional reliability of the intelligent liquid sealing layer 3.

[0039] Fluorocarbon surfactants exhibit typical amphiphilic properties: the hydrophobic end is typically a perfluoroalkyl chain, exhibiting good compatibility with highly fluorinated perfluoropolyether oils; the hydrophilic end contains polar groups such as polyoxyethylene and sulfonic acid groups, which can effectively interact with the internal aqueous phase (e.g., deionized water). This structure significantly reduces the interfacial tension between the perfluoropolyether oil phase and the hydrophilic core 31, allowing the aqueous phase to be uniformly dispersed and completely encapsulated within the oil phase under high-speed shear conditions, forming a stable primary W / O emulsion. During this process, the fluorocarbon surfactant spontaneously accumulates at the water droplet-oil phase interface, forming a dense interfacial film with a certain mechanical strength, effectively inhibiting droplet aggregation, breakage, or sedimentation, thereby ensuring the formation of monodisperse microcapsules within the 3-8 micrometer range. The fluorocarbon surfactant can preferably be selected from one or more of perfluorobutane sulfonate, perfluorooctyl polyoxyethylene ether, difluoroalkyl phosphate, fluorosulfonamide acrylate, perfluorohexylethyl phosphate, perfluorobutylethyl polyoxypropylene ether, and perfluoroalkyl betaine.

[0040] Deionized water, as the main component of the hydrophilic core 31, has a conductivity controlled to ≤0.1 μS / cm. This ensures that even when the microcapsules are densely packed in a high-voltage electric field under normal conditions, they will not form a conductive path or cause local leakage current, thus maintaining the overall high insulation of the intelligent liquid sealing layer 3. At the moment of deflagration, the microcapsule shell ruptures, and the deionized water is rapidly released and exposed to the high-temperature flame. Due to its high latent heat of vaporization, it absorbs a large amount of heat from the fireball and high-temperature gases during the violent vaporization process, achieving rapid cooling, effectively interrupting the combustion chain reaction, and achieving efficient fire extinguishing.

[0041] Furthermore, the hydrophilic core 31 also includes an antifreeze agent and an insulation enhancer; the antifreeze agent is selected from one or more of glycerol, ethylene glycol, propylene glycol, glycerol, and dimethyl sulfoxide; the insulation enhancer is selected from one or more of ammonium borate, ammonium dihydrogen phosphate, sodium tetraborate, and triethanolamine; the amount of antifreeze added is 10%-15% of the mass of deionized water, and the amount of insulation enhancer added is 5%-8% of the mass of deionized water.

[0042] Antifreeze is used to regulate the low-temperature physical properties of the core liquid, ensuring its structural integrity and functional reliability in frigid environments. Antifreeze is miscible with water molecules and significantly lowers the freezing point of the mixed solution through strong hydrogen bonding, effectively preventing mechanical damage caused by low-temperature phase transitions and maintaining the integrity of the microcapsules during long-term storage and service. Simultaneously, antifreeze can increase the overall boiling point of the core mixture and increase its heat of vaporization. After deflagration, the released liquid not only relies on rapid water vaporization for instantaneous strong cooling but also benefits from the continued evaporation of the antifreeze in a higher temperature range, extending the endothermic effect time and enhancing the thermal suppression capability against high-temperature fireballs and arc channels.

[0043] Insulation enhancers not only strengthen electrical insulation performance under normal conditions but also significantly improve fire extinguishing and reignition prevention capabilities after deflagration. For example, ammonium borate, in its untriggered state, is completely soluble in high-purity deionized water. The ions generated by dissociation have low mobility and can effectively suppress the generation of free charge carriers, thereby further improving the volume resistivity and overall insulation resistance of the core liquid. Secondly, in a high-temperature flame environment, ammonium borate decomposes upon heating, releasing ammonia gas that can dilute the local oxygen concentration and inhibit combustion. Simultaneously, the generated boric acid dehydrates at high temperatures, transforming into molten metaboric acid or boron oxide, which can quickly cover exposed metal electrodes or carbonized insulation surfaces. After cooling, it forms a dense, continuous glassy insulating protective film, effectively isolating air gaps between electrodes, blocking the arc reignition path, and fundamentally preventing secondary breakdown. Furthermore, the thermal decomposition process is a strongly endothermic reaction, which can absorb a large amount of additional heat. This, combined with the endothermic effect of water vaporization, further reduces the temperature of the combustion zone and accelerates flame extinguishing.

[0044] The flame extinguishing and explosion relief principle of the intelligent liquid sealing layer 3 is as follows: When a deflagration fault occurs inside the cable joint, generating millisecond-level shock waves and overpressure, the microcapsules rupture rapidly under the action of external shear and sudden pressure changes, releasing the internal functional components. High-purity deionized water, with its extremely high latent heat of vaporization, vaporizes violently, absorbing a large amount of heat from the fireball and high-temperature gas, achieving rapid cooling and effectively interrupting the combustion chain reaction. At the same time, the released perfluoropolyether oil, due to its density being greater than air and its non-flammability, forms a fine, settling non-flammable oil film in the flame area, covering the surface of the burning material, isolating oxygen, and achieving physical suffocation fire extinguishing.

[0045] The preparation method of the intelligent liquid sealing layer 3 includes the following steps:

[0046] S11: Add a fluorocarbon surfactant to the perfluoropolyether oil and stir until completely dissolved to form a homogeneous oil phase;

[0047] S12: Deionized water (or a mixed solution of deionized water, antifreeze and insulating reinforcing agent) is continuously added to the oil phase under high-speed stirring through a conduit with an inner diameter ≤1 mm to form a W / O type emulsion; the stirring speed is 8000-15000 rpm;

[0048] S13: Pour the W / O type emulsion into the polyvinyl alcohol aqueous solution and stir to form a W / O / W type double emulsion;

[0049] S14: Surface curing of W / O / W type dual emulsion yields core-shell structured microcapsules, and several microcapsules are stacked to form a smart liquid sealing layer 3.

[0050] During use, the core-shell structured microcapsules are dispersed in perfluoropolyether oil or low-viscosity silicone oil to form a suspension slurry. The suspension slurry is then injected into the annular cavity of the explosion-proof housing vent of the high-voltage cable joint to form a stable intelligent liquid sealing layer 3.

[0051] Furthermore, in some embodiments, the high-voltage cable joint flame-extinguishing and explosion-proof composite material includes a smart liquid sealing layer 3 and a main liquid protective medium layer 2; the main liquid protective medium layer 2 is located below the smart liquid sealing layer 3. The smart liquid sealing layer 3 is as described above and will not be repeated here.

[0052] The main liquid protective medium layer 2 includes a base liquid; the base liquid includes, by mass percentage: 60%-70% synthetic ester, 20%-30% modified silicone oil and 10%-15% perfluoropolyether oil.

[0053] The synthetic ester is preferably pentaerythritol ester, accounting for 60%-70% of the mass of the main liquid protective dielectric layer 2. As the main continuous phase of this main liquid protective dielectric, the highly branched molecular structure of the synthetic ester endows it with excellent polarity uniformity, high molecular weight, and strong cohesive energy, thereby significantly improving the dielectric strength of the material and effectively supporting the electrical insulation requirements of high-voltage cable joints during long-term operation. Simultaneously, this structure results in a high boiling point (>300°C) and a high flash point (>280°C), significantly reducing the risk of thermal decomposition or combustion under high temperature or partial discharge conditions, enhancing the inherent safety of the system. Furthermore, the synthetic ester molecule contains hydrolyzable ester bonds, making it easily degraded by microorganisms in the natural environment. Its good thermal oxidation stability ensures minimal viscosity change and slow acid value increase under long-term electro-thermal stress, avoiding the generation of corrosive byproducts, thus guaranteeing the long-term chemical and electrical stability of the main liquid protective dielectric layer 2.

[0054] Modified silicone oil constitutes 20%-30% of the main liquid protective medium layer 2 by mass. Its main chain is composed of Si-O bonds, exhibiting an extremely low glass transition temperature and excellent viscosity-temperature characteristics. Its viscosity changes very little over a wide temperature range, significantly improving the fluidity of the entire main liquid protective medium in low-temperature environments. This avoids uneven filling or delayed heat conduction caused by high viscosity, ensuring that the cable joint maintains good heat dissipation and impregnation performance under cold conditions. Simultaneously, the siloxane structure endows it with high thermal stability and low volatility, contributing to improved overall heat resistance of the composite medium. Furthermore, the modified silicone oil's surface polarity is modulated by introducing organic functional groups (such as phenyl, alkoxy, or polyether segments), greatly enhancing its compatibility with highly polar synthetic esters, effectively suppressing phase separation, and promoting uniform dispersion and long-term stable suspension of multiple components such as perfluoropolyether oil, nanoparticles, and flame-retardant additives in the system. Silicone oil itself has high thermal conductivity; its introduction improves the overall thermal conductivity of the composite medium, accelerates heat dissipation from local hot spots, and reduces the risk of insulation aging caused by heat accumulation.

[0055] Perfluoropolyether oil constitutes 10%-15% of the mass of the main liquid protective dielectric layer 2. As a high-performance reinforcing phase, all hydrogen atoms in its molecular structure are replaced by fluorine atoms, forming a highly stable CF and COC bond network. This gives it strong chemical inertness, thermal stability, and dielectric properties, significantly improving the reliability of the main liquid protective dielectric layer 2 under extreme electro-thermal-chemical environments. Perfluoropolyether oil hardly reacts with oxygen, ozone, corona discharge products, or metal catalysts, effectively inhibiting the oxidative degradation of the base liquid under high temperature or partial discharge conditions, thereby extending the service life of the dielectric. Simultaneously, perfluoropolyether oil has extremely high volume resistivity (>1×10⁻⁶). 15 The dielectric strength (Ω·cm) and dielectric strength (≥40 kV / 2.5mm) can be improved by incorporating these properties, which can further enhance the overall insulation level of the composite system.

[0056] The main liquid protective dielectric layer 2 uses a synthetic ester with high dielectric strength, high flash point, and biodegradability as the main continuous phase, exhibiting excellent basic insulation performance and thermal stability. Modified silicone oil, as a performance-adjusting phase, significantly improves the system's flowability and heat dissipation over a wide temperature range due to its excellent viscosity-temperature characteristics and high thermal conductivity. Simultaneously, molecular structure modification enhances its compatibility with polar esters, promoting uniform dispersion of multiple components. A small amount of added perfluoropolyether oil serves as a high-performance reinforcing phase, effectively improving the composite system's insulation limit and long-term chemical stability under extreme conditions due to its excellent chemical inertness, ultra-high dielectric strength, and oxidation resistance. Through molecular polarity matching, interfacial compatibility, and functional complementarity, these three components form a homogeneous and stable system with high flash point, low pour point, high thermal conductivity, high volume resistivity, and excellent anti-aging capabilities, providing fundamental protection for the intelligent flame-quenching and explosion-proof composite material.

[0057] To further enhance the protective performance of the main liquid protective medium layer 2, the main liquid protective medium layer 2 may also include nano-SiO2 particles, nano-Al2O3 particles, and flame retardants; the amount of nano-SiO2 particles added is 3%-5% of the mass of the base liquid; the amount of nano-Al2O3 particles added is 2%-3% of the mass of the base liquid; and the amount of flame retardant added is 5%-8% of the mass of the base liquid.

[0058] After surface modification with a silane coupling agent, nano-SiO2 particles serve as the core functional component for achieving a reversible shear thickening effect, playing a dynamic mechanical response role in the main liquid protective medium layer 2. Under normal low-shear conditions, they are uniformly and stably dispersed in the liquid phase with a particle size of 20-50 nm, having little impact on the system's rheological properties. However, when subjected to high strain rate loads such as explosive impacts, the particles rapidly form a temporary network structure dominated by hydrogen bonds or van der Waals forces due to instantaneous compression and relative motion, and may even undergo frictional locking, leading to a sharp increase in the system viscosity and even exhibiting near-solid-state behavior. This effectively absorbs, dissipates, and disperses the impact kinetic energy. Once the external force is removed, this physical network immediately dissociates, and the fluid returns to its initial fluidity, achieving a reversible response.

[0059] After surface modification with stearic acid, nano-Al2O3 particles are primarily used for active insulation protection under arc fault conditions. In the high-temperature environment generated by partial discharge or arcing, the Al2O3 particles rapidly melt and sinter on the surface of metal electrodes or carbonized insulation, forming a dense, high-hardness, and highly insulating alumina ceramic layer. This effectively covers the exposed conductor, blocks the conductive channels between electrodes, and fundamentally inhibits arc reignition. Stearic acid modification, by introducing long-chain alkyl groups onto its surface, significantly improves the wettability and dispersion stability of the nanoparticles in non-polar or weakly polar base liquids, avoiding sedimentation failure due to agglomeration and ensuring uniform distribution and immediate response capability during long-term service.

[0060] Organophosphorus flame retardants achieve high-efficiency flame retardancy through a synergistic dual mechanism of gas-phase and condensed-phase combustion. Under high-temperature pyrolysis conditions, they first decompose to generate phosphorus-containing compounds such as phosphoric acid and polyphosphoric acid, catalyzing the dehydration and cross-linking of the base liquid and surrounding organic materials to form a dense char layer (condensed-phase flame retardancy), isolating heat and combustible gas transfer. Simultaneously, they release phosphorus-containing free radicals such as PO· and HPO·, efficiently capturing H· and OH· free radicals in the combustion chain reaction and interrupting flame propagation (gas-phase flame retardancy). Compared to halogenated or inorganic flame retardants, organophosphorus compounds have excellent compatibility with oily media, are less prone to precipitation, and their thermal decomposition products are mostly non-conductive substances, having little impact on the dielectric properties of the composite medium. Therefore, achieving high-efficiency flame retardancy while ensuring electrical safety makes them ideal flame-retardant functional additives in this system.

[0061] The preparation method of the main liquid protective medium layer 2 includes the following steps:

[0062] S21: Surface pretreatment of nano-SiO2 and nano-Al2O3: Nano-SiO2 is grafted with a silane coupling agent (such as KH-550) under an inert atmosphere to change its surface from hydrophilic to hydrophobic; nano-Al2O3 is surface-modified with stearic acid; the modified nano-SiO2 and nano-Al2O3 powders are mixed with a portion of the base liquid for pre-dispersion, and then prepared into a uniform and stable nanoparticle mother liquor by high-speed shear dispersion or ultrasonic treatment;

[0063] S22: Preparation of base liquid: Mix synthetic ester and modified silicone oil in proportion, heat and stir evenly at 60-70℃ under protective atmosphere, and after the temperature drops to 40-50℃, add perfluoropolyether oil and stir to form a uniform and transparent mixed base liquid.

[0064] S23: Slowly add the nanoparticle mother liquor to the mixed base liquid, stir evenly at 40-50℃, then add the organophosphorus flame retardant, stir until completely dissolved, filter, and vacuum degas to obtain the main liquid protective medium layer 2.

[0065] like Figures 1 to 4 As shown, this embodiment of the invention also provides a high-voltage cable joint flame extinguishing and explosion relief device, including an explosion-proof housing 1, a main liquid protective medium layer 2, an intelligent liquid sealing layer 3, and an explosion relief port mechanism 4.

[0066] The explosion-proof enclosure 1 has a closed inner cavity to accommodate and protect the high-voltage cable connector 6, ensuring it remains in a controlled environment under both normal operation and fault conditions. Figure 1 and Figure 2 As shown, the explosion-proof housing 1 adopts an axially split structure, consisting of two semi-shells symmetrically arranged along its axis—an upper housing 11 and a lower housing 12. The two semi-shells are detachably assembled via flanges 13 and connecting bolts 14, forming an integral housing with a closed cavity after assembly, which facilitates on-site installation, maintenance, and replacement of internal components.

[0067] The explosion-proof housing 1 is preferably made of high-strength carbon fiber reinforced thermosetting resin matrix composite material, which combines excellent mechanical strength, corrosion resistance, and lightweight characteristics, effectively confining the shock wave generated in the initial stage of an explosion and preventing the housing from rupturing. The thickness of the explosion-proof housing 1 can be designed to be 10-20 mm, preferably 15 mm, ensuring sufficient blast resistance while meeting the requirements of lightweight design. Finite element simulation and actual explosion tests have verified that this thickness can effectively confine the initial shock wave when a short-circuit arc explosion occurs inside the high-voltage cable joint 6, preventing the housing from shattering and thus limiting the explosion energy to a controllable range.

[0068] At both ends of the explosion-proof housing 1 along its axial direction, there are cable sealing interfaces 5 that communicate with the inner cavity, used for introducing and fixing high-voltage cables. Figure 2 As shown, the cable sealing interface 5 is equipped with a multi-layer composite annular sealing structure. This structure, from the inside out, includes an elastic sealing ring 51 and a flame-retardant and waterproof layer 52. The elastic sealing ring 51 is made of silicone rubber, fluororubber, or other highly elastic and temperature-resistant polymers, possessing excellent compression resilience and aging resistance. It can form a tight initial seal on the cable outer sheath surface, effectively preventing gap leakage caused by cable fretting or thermal expansion and contraction. The flame-retardant and waterproof layer 52 is filled with flame-retardant silicone or modified epoxy resin, combining waterproof, dustproof, and flame-retardant functions. It effectively prevents external environmental intrusion and forms a fire barrier at the interface, inhibiting the spread of flames along the cable channel. This composite annular sealing structure ensures high sealing performance during normal operation and the initial stage of an explosion, providing a stable working environment for the internal liquid medium and preventing external media such as moisture and oxygen from interfering with insulation performance.

[0069] The main liquid protective medium layer 2 fills the inner cavity of the explosion-proof housing 1, completely immersing the high-voltage cable joint 6 to ensure reliable electrical insulation under normal operating conditions. The main liquid protective medium layer 2 consists of a base liquid and functional additives.

[0070] The base fluid adopts a ternary mixture system, comprising, by mass percentage: 60%-70% synthetic ester, 20%-30% modified silicone oil, and 10%-15% perfluoropolyether oil. The preferred synthetic ester is pentaerythritol ester, which possesses high dielectric strength (>40 kV / 2.5 mm), high flash point (>280℃), good biodegradability, and excellent thermal stability. The modified silicone oil improves fluidity and thermal conductivity (≥0.15 W / (m·K)) and enhances heat transfer efficiency. The perfluoropolyether oil enhances oxidation resistance and long-term insulation stability, ensuring efficient operation even after prolonged use. The high-flash-point synthetic ester and other components in the base fluid undergo endothermic vaporization at high temperatures, consuming a large amount of heat energy, rapidly reducing local temperature, and slowing the rate of pressure rise.

[0071] Functional additives include nano-SiO2 particles, nano-Al2O3 particles, and flame retardants. The amount of nano-SiO2 particles added is 3%-5% of the base liquid mass. When encountering the high shear rate generated by an explosive shock wave, these particles can rapidly form a three-dimensional network structure, triggering the shear thickening effect (STF), and instantly transforming into a solid-like state to absorb and buffer the impact energy. The surface of the nano-SiO2 particles can be modified with a silane coupling agent to improve their dispersibility and interfacial adhesion. The amount of nano-Al2O3 particles added is 2%-3% of the base liquid mass. When exposed to the high temperature of an electric arc, they migrate to the electrode surface and deposit to form a dense insulating repair film, effectively inhibiting secondary breakdown. In addition, an organophosphorus flame retardant is selected as the flame retardant component, added at 5%-8% of the base liquid mass. The phosphoric acid substances generated by its decomposition at high temperatures can form a char layer at the combustion interface, interrupting the free radical chain reaction, thereby achieving a chemical flame-suppressing effect.

[0072] The above components work together to enable the main liquid protective medium layer 2 to perform triple protection functions of heat absorption vaporization cooling, shear thickening buffering, and chemical flame retardant inhibition when facing the complex environment in the early stage of an explosion, thus constructing the first active protection barrier. After the failure, the residual liquid film automatically fills the burning defects, achieving partial self-recovery of insulation performance.

[0073] like Figure 4 As shown, the explosion vent mechanism 4 is integrally integrated on the side wall of the explosion-proof housing 1. The explosion vent mechanism 4 includes a connecting seat 41, an explosion vent cover 43, and an elastic reset member 44.

[0074] The connecting seat 41 is an annular or cylindrical structure fixedly embedded in the wall of the explosion-proof housing 1. It has an internal pressure relief channel that penetrates the wall thickness of the explosion-proof housing 1. One end of this pressure relief channel communicates with the inner cavity of the explosion-proof housing 1, and the other end leads to the external environment. An annular chamber 33 is provided in the circumferential region of the pressure relief channel near the inner cavity for pre-installing the intelligent liquid sealing layer 3.

[0075] The explosion relief cover 43 is made of high-temperature resistant stainless steel. Under normal conditions, it tightly covers and seals the opening of the pressure relief channel to prevent internal media leakage and external environmental intrusion. To ensure sealing reliability, a sealing gasket 42 is provided between the contact surface of the explosion relief cover 43 and the connecting seat 41. The sealing gasket 42 can be made of metal spiral wound gasket, fluororubber O-ring or ceramic fiber composite gasket, etc., and is dynamically matched according to the operating temperature and pressure.

[0076] One end of the explosion vent cover 43 is rotatably connected to one side of the connecting seat 41 via a hinge mechanism (such as a pin or a flexible metal shaft), and the other end of the explosion vent cover 43 is elastically pressed against the opposite side of the connecting seat 41 via an elastic reset member 44.

[0077] The elastic reset element 44 is preferably a high-stiffness helical spring, disc spring assembly, or constant force spring structure. Its preload is precisely calculated and experimentally calibrated to ensure that the opening pressure threshold of the entire explosion relief mechanism 4 is set within the range of 0.5-1.0 MPa, preferably 0.8 MPa. This threshold is higher than the internal pressure fluctuation range during normal operation, and also ensures timely response during the rapid pressure rise phase in the early stage of an explosion, preventing structural damage to the casing due to overpressure.

[0078] When an arc explosion occurs in the inner cavity of the explosion-proof housing 1 due to a cable joint failure, and the internal pressure rapidly rises and exceeds a set threshold, the net pressure acting on the inner side of the explosion relief cover 43 overcomes the preload of the elastic reset member 44, driving the explosion relief cover 43 to instantly flip upward around the hinge and open, achieving millisecond-level overpressure relief. This process not only effectively releases the internal high-pressure gas and reduces the mechanical load on the housing, but also causes the high-speed airflow to simultaneously impact the intelligent liquid sealing layer 3 in the annular chamber 33, triggering its atomization and spraying it into the pressure relief channel and the external fire scene, achieving active fire suppression. After the pressure relief is completed, as the internal cavity pressure rapidly decreases, the elastic reset member 44 immediately rebounds, driving the explosion relief cover 43 to automatically reset and close within ≤2 seconds, re-establishing a sealing state. On the one hand, this prevents the continuous influx of oxygen-rich air from causing reignition; on the other hand, it works with the internal oxygen-consuming environment to create an oxygen-deficient asphyxiation space, completely extinguishing any remaining flames.

[0079] like Figure 3 As shown, the intelligent liquid sealing layer 3 is pre-placed in the annular chamber 33 inside the pressure relief channel of the explosion relief mechanism 4. Under normal operating conditions, the intelligent liquid sealing layer 3 exists in a continuous and stable liquid phase, forming an efficient and reliable dynamic liquid sealing barrier that tightly seals the entire flow section of the pressure relief channel. This not only effectively prevents leakage of the internal main liquid protective medium layer 2 due to long-term static placement or micro-pressure fluctuations, but also blocks external air, moisture, and dust from entering the shell, thereby maintaining the cleanliness and insulation stability of the internal environment.

[0080] The intelligent liquid sealing layer 3 is a stable dispersion system composed of millions of core-shell structured microcapsules. Each microcapsule includes: a hydrophilic core 31, a hydrophobic shell 32, and an interface layer.

[0081] The hydrophilic core 31 is based on ultrapure deionized water (conductivity ≤0.1μS / cm), with antifreeze and insulation enhancer added as auxiliary additives. The antifreeze is selected from one or more of glycerol, ethylene glycol, propylene glycol, glycerol, and dimethyl sulfoxide, and its addition amount is 10%-15% of the mass of deionized water, which can effectively reduce the freezing point of the system and ensure stability in low-temperature environments. The insulation enhancer is preferably selected from one or more of ammonium borate, ammonium dihydrogen phosphate, sodium tetraborate, and triethanolamine, and its addition amount is 5%-8% of the mass of deionized water, which is used to improve the dielectric properties of the atomized droplets.

[0082] The hydrophobic outer shell 32 is made of perfluoropolyether oil (PFPE) with a molecular weight of 2000-3000, a kinematic viscosity of 80-120 cSt at 25°C, and a dielectric strength ≥40 kV / 2.5 mm. It is non-flammable, chemically inert, and highly insulating, forming a dense, flexible, and electrically insulating coating at room temperature. This effectively isolates the core moisture from the external oil phase environment, preventing droplet fusion or component migration. Furthermore, perfluoropolyether oil has excellent film-forming properties, spreading into a continuous liquid film at high temperatures, further enhancing fire extinguishing performance.

[0083] The interfacial layer is a fluorocarbon surfactant with a typical amphiphilic molecular structure: the hydrophobic end is usually a perfluoroalkyl chain, which has good compatibility with highly fluorinated perfluoropolyether oil; the hydrophilic end contains polar groups such as polyoxyethylene and sulfonic acid groups, which can effectively interact with the inner aqueous phase (such as deionized water). This structure significantly reduces the interfacial tension between the perfluoropolyether oil phase and the hydrophilic core 31, allowing the aqueous phase to be uniformly dispersed and completely encapsulated in the oil phase under high-speed shear conditions, forming a stable primary W / O emulsion. The fluorocarbon surfactant can preferably be selected from one or more of perfluorobutane sulfonate, perfluorooctyl polyoxyethylene ether, difluoroalkyl phosphate, fluorosulfonamide acrylate, perfluorohexylethyl phosphate, perfluorobutylethyl polyoxypropylene ether, and perfluoroalkyl betaine.

[0084] When a short-circuit arc explosion occurs inside the high-voltage cable joint 6, the pressure inside the explosion-proof housing 1 rapidly rises and reaches the explosion relief threshold (≥0.8 MPa). High-pressure gas flows at high speed through the pressure relief channel, exerting strong shearing and impact on the intelligent liquid sealing layer 3 within the annular chamber 33. This causes the interface of the core-shell structure microcapsules to be instantly destroyed, the hydrophobic outer shell 32 ruptures, and the hydrophilic core 31 is released. Under the shearing action of the high-speed airflow, the core rapidly and efficiently atomizes, forming a large number of submicron to micron-sized composite droplet clouds. These atomized droplets are then sprayed into the pressure relief channel and the external fire area. The hydrophilic core 31 utilizes the high latent heat of vaporization of water for violent vaporization, rapidly absorbing heat and cooling down. Simultaneously, the hydrophobic outer shell 32 forms a continuous insulating liquid curtain, covering the surface of combustible materials, isolating oxygen, and inhibiting the diffusion of volatile combustible gases. The synergistic effect of this "cooling + oxygen isolation" dual fire extinguishing mechanism not only efficiently extinguishes the flames but also transforms the traditional passive pressure relief channel into an outlet with active fire extinguishing capabilities, achieving simultaneous and deep integration of pressure relief and fire extinguishing.

[0085] The high-voltage cable joint flame extinguishing and explosion relief device of this invention achieves closed-loop control throughout the entire process, from energy suppression and active fire extinguishing and pressure relief to environmental self-recovery, through a triple-layered, deeply coordinated active protection mechanism. The entire fire extinguishing and pressure relief process is as follows:

[0086] First, in the initial stage of the explosion, the first layer of protection—the energy absorption mechanism—is immediately activated. The dispersed nano-SiO2 particles in the main liquid protective medium layer 2 rapidly aggregate to form a three-dimensional network structure under high shear rate impact, triggering a shear thickening effect. This causes a sharp increase in the local viscosity of the main liquid protective medium layer 2, resulting in a near-solid state, thus efficiently absorbing, dissipating, and buffering the energy of the explosion shock wave. Simultaneously, nano-Al2O3 particles migrate towards the electrodes or ablation areas under the high-temperature field of the electric arc, depositing a dense, highly insulating alumina-based protective film on the metal or carbonized surface. This effectively isolates the conductive channels between electrodes, suppressing secondary breakdown and arc reignition. Furthermore, components such as high-flash-point synthetic esters in the base liquid of the main liquid protective medium layer 2 undergo endothermic vaporization at high temperatures, consuming a large amount of heat energy, rapidly reducing the local temperature, and slowing the rate of pressure rise, thereby preventing further chain reactions or fires caused by high temperatures.

[0087] As the internal pressure continues to increase and reaches a preset threshold (≥0.8 MPa), the system automatically enters the second layer of protection—the active fire extinguishing and pressure relief stage. At this time, the overpressure triggers the opening of the explosion relief cover 43 in the explosion relief port mechanism 4. Simultaneously, the intelligent liquid sealing layer 3, which is pre-installed in the annular chamber 33 inside the pressure relief channel, is activated. The impact of the high-speed airflow causes the microcapsules of the core-shell structure in the intelligent liquid sealing layer 3 to rupture and rapidly atomize, generating a large number of tiny droplets. After these droplets are sprayed into the pressure relief channel and the external fire area, the hydrophilic core 31 rapidly vaporizes and absorbs heat, significantly reducing the surrounding temperature, while the hydrophobic outer shell 32 forms a continuous insulating film, covering the surface of combustibles, blocking the oxygen supply and inhibiting the diffusion of volatile combustible gases, achieving a dual fire extinguishing effect of "cooling + oxygen isolation".

[0088] Finally, after completing the fire extinguishing mission, the device enters the third layer of protection—the environmental self-recovery phase. After depressurization, the internal cavity pressure drops rapidly, and the elastic reset component 44 drives the explosion relief cover 43 to automatically close within ≤2 seconds, rebuilding the sealed environment. This rapid reset mechanism effectively blocks the continuous influx of external oxygen-rich air, preventing reignition; simultaneously, a large amount of internal oxygen has been consumed during the explosion, which, together with the remaining main liquid protective medium layer 2 and the deposited perfluoropolyether oil film, creates a low-oxygen asphyxiation environment, completely extinguishing any remaining flames. During the explosion impact phase, the main liquid protective medium layer 2 temporarily exhibits a near-solid state due to shear thickening. As the temperature rapidly decreases, its viscosity drops, restoring it to a highly fluid liquid state, allowing it to be redistributed evenly within the cavity, continuously providing electrical insulation. It also works synergistically with the repair film formed by nano-Al2O3 to automatically fill micropores, cracks, or interface defects caused by arc ablation, achieving the environmental self-recovery function.

[0089] The high-voltage cable joint flame extinguishing and explosion relief device provided in this embodiment of the invention includes an explosion-proof housing 1, a main liquid protective medium layer 2, an intelligent liquid sealing layer 3, and an explosion relief port mechanism 4, which together constitute a triple collaborative protection system integrating energy absorption, active fire extinguishing and pressure relief, and environmental self-recovery. When an arc explosion occurs at the high-voltage cable joint 6, the main liquid protective medium layer 2 first absorbs the impact energy using the shear thickening effect of nano-SiO2 and suppresses the temperature rise through vaporization heat absorption. At the same time, nano-Al2O3 migrates at high temperature to form an insulating repair film. As the internal pressure rapidly rises to the set threshold, the explosion relief mechanism 4 opens instantly, simultaneously triggering the rupture and atomization of the core-shell structure droplets in the intelligent liquid sealing layer 3. Its hydrophilic core vaporizes violently to achieve efficient cooling, while the hydrophobic shell spreads out as a non-flammable liquid curtain to isolate oxygen, transforming the traditional pressure relief channel into an active fire extinguishing outlet that "extinguishes as soon as it is released". Subsequently, the elastic reset component 44 drives the explosion relief cover 43 to close automatically, rebuilding the sealing environment. Combined with the internal oxygen consumption state and the residual highly insulating liquid components, it quickly constructs low-oxygen asphyxiation and insulation recovery conditions. The main liquid medium restores its fluidity after cooling and works in conjunction with the repair film to fill ablation defects, achieving self-repair function. The device of this invention integrates energy absorption, active fire suppression and pressure relief, and environmental self-recovery through triple deep collaborative protection, forming a closed-loop intervention throughout the entire process. Its response relies entirely on physical and chemical mechanisms, requiring no external energy or control signals, and can be autonomously activated within milliseconds, significantly reducing operation and maintenance costs and power outage time, and greatly improving the safety resilience and power supply reliability of the power system.

[0090] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A flame-quenching and explosion-proof composite material for high-voltage cable joints, characterized in that, include: A smart liquid sealing layer; the smart liquid sealing layer is composed of multiple core-shell structured microcapsules; each microcapsule includes a hydrophilic core, a hydrophobic shell, and an interface layer; the hydrophobic shell covers the periphery of the hydrophilic core, and the interface layer is located between the hydrophilic core and the hydrophobic shell; the main component of the hydrophilic core is deionized water; the main component of the hydrophobic shell is perfluoropolyether oil; and the interface layer is a fluorocarbon surfactant.

2. The high-voltage cable joint flame-quenching and explosion-proof composite material according to claim 1, characterized in that, The hydrophilic core also includes an antifreeze agent and an insulating reinforcing agent; the antifreeze agent is selected from one or more of glycerol, ethylene glycol, propylene glycol, glycerol, and dimethyl sulfoxide; the insulating reinforcing agent is selected from one or more of ammonium borate, ammonium dihydrogen phosphate, sodium tetraborate, and triethanolamine; the amount of antifreeze agent added is 10%-15% of the mass of deionized water, and the amount of insulating reinforcing agent added is 5%-8% of the mass of deionized water.

3. The high-voltage cable joint flame-quenching and explosion-proof composite material according to claim 1, characterized in that, The perfluoropolyether oil has a molecular weight of 2000-3000, a kinematic viscosity of 80-120 cSt at 25°C, and a dielectric strength ≥40kV / 2.5mm.

4. The high-voltage cable joint flame-quenching and explosion-proof composite material according to claim 1, characterized in that, The fluorocarbon surfactant is selected from one or more of perfluorobutane sulfonate, perfluorooctyl polyoxyethylene ether, difluoroalkyl phosphate, fluorosulfonamide acrylate, perfluorohexyl ethyl phosphate, perfluorobutyl ethyl polyoxypropylene ether, and perfluoroalkyl betaine.

5. The high-voltage cable joint flame-quenching and explosion-proof composite material according to claim 1, characterized in that, Also includes: Main liquid protective medium layer; The main liquid protective medium layer is located below the intelligent liquid sealing layer according to any one of claims 1-4; The main liquid protective medium layer includes a base liquid; the base liquid, by mass percentage, includes: 60%-70% synthetic ester, 20%-30% modified silicone oil, and 10%-15% perfluoropolyether oil.

6. The high-voltage cable joint flame-quenching and explosion-proof composite material according to claim 5, characterized in that, The main liquid protective medium layer also includes functional additives; the functional additives include nano-SiO2 particles, nano-Al2O3 particles and flame retardants; the amount of nano-SiO2 particles added is 3%-5% of the mass of the base liquid; the amount of nano-Al2O3 particles added is 2%-3% of the mass of the base liquid; and the amount of flame retardant added is 5%-8% of the mass of the base liquid.

7. A method for preparing a high-voltage cable joint flame-quenching and explosion-proof composite material as described in any one of claims 1-4, characterized in that, Includes the following steps: S11: Add a fluorocarbon surfactant to the perfluoropolyether oil and stir until completely dissolved to form a homogeneous oil phase; S12: Deionized water is continuously added to the stirred oil phase through a conduit with an inner diameter ≤1 mm to form a W / O type emulsion; S13: Pour the W / O type emulsion into the polyvinyl alcohol aqueous solution and stir to form a W / O / W type double emulsion; S14: Surface curing of W / O / W type dual emulsion yields core-shell structured microcapsules, and several microcapsules are stacked to form an intelligent liquid sealing layer.

8. A flame extinguishing and explosion relief device for a high-voltage cable joint, characterized in that, include: Explosion-proof housing, explosion vent mechanism, and the flame-extinguishing and explosion-venting composite material for high-voltage cable joints as described in any one of claims 5 or 6; The explosion-proof housing has an inner cavity; the explosion-proof housing has cable sealing interfaces communicating with the inner cavity at both ends along its axis; the main liquid protective medium layer fills the inner cavity of the explosion-proof housing and is used to immerse the high-voltage cable joint located in the inner cavity; The explosion relief mechanism includes a pressure relief channel and an explosion relief cover plate; the pressure relief channel is disposed on the explosion-proof housing and communicates with the inner cavity; the explosion relief cover plate is used to cover and seal the pressure relief channel; an annular chamber is provided inside the pressure relief channel; the intelligent liquid sealing layer is disposed inside the annular chamber.

9. The high-voltage cable joint flame extinguishing and explosion relief device according to claim 1, characterized in that, The explosion vent mechanism also includes an elastic reset component; one end of the explosion vent cover is rotatably connected to one side of the pressure relief channel via a hinge structure, and the other end of the explosion vent cover is elastically connected to the other side of the pressure relief channel via the elastic reset component.

10. The high-voltage cable joint flame extinguishing and explosion relief device according to claim 1, characterized in that, The explosion-proof housing has an annular sealing structure at the cable sealing interface, which includes an elastic sealing ring and a flame-retardant and waterproof layer disposed outside the elastic sealing ring.

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