A 1kv crosslinked polyethylene insulated cable

Abstract

This invention discloses a 1kV cross-linked polyethylene insulated cable, which consists of a cable core, a shielding layer, a ceramic membrane, a sheath, and armor from the inside out. The cable core is obtained by extruding cross-linked polyethylene material onto the outside of a conductor, followed by stranding the conductor core. The ceramic membrane is made of halloysite nanotubes. The sheath is obtained by extruding cross-linked polyethylene material onto the outside of the ceramic membrane. The cross-linked polyethylene material is obtained by melt blending, fluorination, and adding a cross-linking agent to polyethylene as raw materials, followed by compounding. The modified basalt fiber is obtained by first surface-modifying basalt fiber with nano-silica to obtain pretreated fiber, and then organically modifying it with polyethylene. This cable has excellent anti-aging properties, greatly extending its service life and ensuring power supply safety.

Description

Technical Field

[0001] This invention belongs to the field of cable processing technology, and specifically relates to a 1kV cross-linked polyethylene insulated cable. Background Technology

[0002] Cables are used to transmit and distribute electrical energy. They consist of a conductor (copper or aluminum, which have good conductivity), an insulation layer, a shielding layer, a sheath, and armor. They are used in urban power grids, power plant leads, underwater transmission lines, and other fields. In cable construction, the insulation layer serves to isolate the conductor from the external environment and from each other.

[0003] 1kV cables are commonly used in medium and low voltage power distribution networks, primarily in three-phase four-wire systems, with an effective phase voltage of 0.6kV. Common insulation materials for 1kV cables include cross-linked polyethylene (XLPE), polyvinyl chloride (PVC), and low-density polyethylene (LDPE). XLPE cables are more widely used due to their high volume resistivity, low dielectric loss, good heat aging resistance, good stress cracking resistance, ease of processing, and low cost.

[0004] Cross-linked polyethylene (XLPE) is obtained by forming a cross-linked structure between polyethylene molecular chains through chemical or physical methods. XLPE cables exhibit high insulation resistance, low dielectric loss, and excellent electrical properties. Furthermore, XLPE cables possess good heat resistance, mechanical properties, and resistance to environmental stress cracking, enabling them to operate normally under certain temperature and mechanical stress conditions, ensuring the safety and stability of power transmission.

[0005] Currently, there are three main methods for preparing cross-linked polyethylene: peroxide cross-linking, radiation cross-linking, and silane cross-linking. Silane cross-linked polyethylene is made by grafting or copolymerizing cross-linkable alkoxysilanes onto the polyethylene backbone. It does not require specialized cross-linking equipment, has simple process control, and is widely used. However, the resulting cross-linked polyethylene insulated cables have poor abrasion resistance and general aging resistance, resulting in a short service life.

[0006] Patent application CN119673543A discloses a 0.6 / 1kV cross-linked polyethylene cable, comprising a core, a cross-linked polyethylene underlayer, a protective outer layer, and a composite protective layer. The composite protective layer is made by mixing expanded graphite with a thermally responsive hardening agent and forms a coating over the cross-linked polyethylene underlayer. When the thermally responsive hardening agent is heated and at a thermal reaction temperature, it generates a solid hard material to improve the hardness of the composite protective layer. The heat-responsive hardening agent described in this patent application generates a high-hardness solid material when heated to its reaction temperature. The expansion of the expanded graphite and the formation of the solid material by the heat-responsive hardening agent ensure that the composite protective layer maintains good hardness. This allows the composite protective layer to withstand impacts during heating, preventing a significant decrease in impact resistance due to the expansion of the graphite. This effectively protects the cross-linked polyethylene underlayer and its internal core even after impacts during heating. However, this patent application primarily improves the cable's impact resistance; its anti-aging performance is not significantly improved. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a 1kV cross-linked polyethylene insulated cable.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A 1kV cross-linked polyethylene insulated cable is composed of a cable core, a shielding layer, a ceramic membrane, a sheath, and armor from the inside out. The cable core is obtained by extruding cross-linked polyethylene material onto the outside of a conductor, followed by stranding the conductor core. The ceramic membrane is made of halloysite nanotubes. The sheath is obtained by extruding cross-linked polyethylene material onto the outside of the ceramic membrane. The cross-linked polyethylene material is obtained by melt blending, fluorination, adding a cross-linking agent, and mixing of polyethylene, calcium oxide-doped boron nitride aerogel, and modified basalt fiber as raw materials. The modified basalt fiber is obtained by first surface modification of basalt fiber with nano-silica to obtain pretreated fiber, followed by organic modification with polyethylene.

[0010] Preferably, the conductor is made by first forming a single fiber core from an oxygen-free copper rod with a copper content of 99 wt.% or more, and then twisting 6 to 8 fiber cores together.

[0011] Preferably, the shielding layer is formed by braiding tin-plated copper wires on the outside of the cable core; the ceramic film is tightly attached to the surface of the shielding layer and completely wraps around it; the armor is formed by wrapping steel strips around the outside of the sheath.

[0012] Preferably, the ceramic membrane is prepared by the following method, by weight: 1 part halloysite nanotubes are added to 6-8 parts anhydrous ethanol and stirred until homogeneous. Then, 0.1-0.2 parts of triethoxyoctylsilane are added and stirred until homogeneous. The mixture is stirred at 100-120°C for 5-6 hours, and the precipitate is collected by centrifugation to obtain modified halloysite nanotubes. The modified halloysite nanotubes are then ultrasonically dispersed in 6-8 parts of organic solvent, and 3-4 parts of polystyrene are added. The mixture is further ultrasonically dispersed until homogeneous to obtain a spinning solution. The solution is electrospun and sintered to obtain the ceramic membrane.

[0013] More preferably, the organic solvent is obtained by mixing N,N-dimethylformamide and tetrahydrofuran in equal mass.

[0014] Further preferred electrospinning conditions are: voltage 5-7 kV, needle inner diameter 0.3-0.5 mm, spinning solution pumping speed 50-60 μL / min, distance between needle and collecting roller 8-10 cm, diameter of collecting roller 10-12 cm, and rotation speed 2000-3000 r / min.

[0015] Further preferred sintering conditions are: heating to 900-950℃ at 15-20℃ / min and holding for sintering for 5-7 hours.

[0016] Preferably, the calcium oxide-doped boron nitride aerogel is prepared by the following method, by weight: First, 4 parts calcium nitrate, 1 part sodium silicate, and 1.5 parts triethylamine are dissolved in 5-7 parts of a 70-80% (v / v) ethanol solution, heated to reflux, and stirred for 30-40 minutes to obtain a calcium silicate solution; then, 1 part boric acid and 1 part melamine are added to 5-7 parts acetone, and stirred at 60-70°C until transparent to obtain a boron nitride precursor solution; finally, the calcium silicate solution is added to the boron nitride precursor solution, and the mixture is allowed to stand at -20 to -30°C for 12-15 hours, supercritically dried, and calcined at 400-500°C for 10-12 hours in air to obtain the final product.

[0017] Preferably, in preparing the cross-linked polyethylene material, the mass ratio of polyethylene, calcium oxide-doped boron nitride aerogel, modified basalt fiber, and cross-linking agent is 10:0.7-0.9:0.5-0.7:0.3-0.4; the cross-linking agent is dicumyl peroxide.

[0018] Preferably, a torque rheometer is used for melt blending, with the following conditions: temperature 135-145℃, rotation speed 40-50 rpm, and time 30-40 minutes.

[0019] Preferably, the fluorination treatment involves transferring the molten blended product into a sealed space containing fluorine gas and allowing it to stand for 8 to 10 hours under a magnetic field of 2 to 3T. The gas in the sealed space consists of air and fluorine gas, with the volume percentage of fluorine gas being 3 to 5%.

[0020] Preferably, a two-roll mill is used for mixing, with a mixing temperature of 120-130°C and a mixing time of 8-10 minutes.

[0021] Preferably, the specific method for surface modification of basalt fibers using nano-silica in the preparation of modified basalt fibers is as follows: First, the basalt fibers are immersed in a 3-5 mol / L hydrochloric acid solution at 10-12 times their weight, and then ultrasonically treated at 400-500 W for 50-60 minutes at 60-70°C. After filtration, the fibers are washed with water until neutral and dried to obtain acid-treated basalt fibers. Then, the nano-silica is ultrasonically dispersed in a solution at a volume concentration of 85-90% at 10-12 times their weight. A nano-silica dispersion was obtained by adding γ-aminopropyltriethoxysilane to a 15-20 times its weight volume of an 85-90% ethanol solution and stirring for 1-2 hours. The nano-silica dispersion was then added, and stirring was continued for 1-2 hours. Finally, acid-treated basalt fibers were added, and stirring was carried out for 3-4 hours. The precipitate was collected by centrifugation, washed with water, and dried. The mass ratio of basalt fibers, nano-silica, and γ-aminopropyltriethoxysilane was 1:0.1-0.2:1-2.

[0022] More preferably, the basalt fiber is short-cut basalt fiber.

[0023] Preferably, the specific method for organic modification using polyethylene in the preparation of modified basalt fiber is as follows: after mixing polyethylene and pretreated fiber evenly at a mass ratio of 10:3 to 5, the mixture is extruded by twin screw extrusion.

[0024] Further preferably, the temperatures of each zone of the twin-screw extrusion are, in order: 160–170℃, 180–190℃, 210–220℃, and 170–180℃; and the screw speed is 200–250 r / min.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention provides a 1kV cross-linked polyethylene (XLPE) insulated cable, which consists of a cable core, a shielding layer, a ceramic membrane, a sheath, and armor from the inside out. The cable core is obtained by extruding XLPE material onto the outside of a conductor, followed by stranding the conductor core. The ceramic membrane is made of halloysite nanotubes. The sheath is obtained by extruding XLPE material onto the outside of the ceramic membrane. The XLPE material is obtained by melt blending, fluorination, and adding a cross-linking agent to polyethylene, using polyethylene, calcium oxide-doped boron nitride aerogel, and modified basalt fiber as raw materials. The modified basalt fiber is obtained by first surface-modifying basalt fiber with nano-silica to obtain pretreated fiber, and then organically modifying it with polyethylene. This cable has excellent anti-aging properties, greatly extending its service life and ensuring power supply safety.

[0027] This invention places a ceramic membrane between the shielding layer and the sheath. The ceramic membrane is made of halloysite nanotubes and contains abundant pores, which promotes the bonding between the sheath and the shielding layer and provides the most basic guarantee for the anti-aging performance of the sheath. In addition, the ceramic membrane has excellent mechanical properties and stability and can work synergistically with the sheath to help improve the anti-aging performance.

[0028] The core of this invention lies in cross-linked polyethylene material, which is prepared from polyethylene, calcium oxide-doped boron nitride aerogel, and modified basalt fiber. On the one hand, the porous structure of the calcium oxide-doped boron nitride aerogel promotes the full cross-linking of the cross-linked polyethylene material, and the fibrous modified basalt fiber is interwoven in the pores, making the product structure more compact and improving the product's insulation properties. On the other hand, boron nitride and basalt fiber have excellent anti-aging properties. This invention, through their synergistic effect, as well as calcium oxide doping treatment of boron nitride and nano-silica modification of basalt fiber, synergistically improves the anti-aging properties of the product. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] The polyethylene involved in this invention is low-density polyethylene, grade LD165, manufactured by Yanshan Petrochemical; basalt fiber, 3mm in length, manufactured by Lingshou County Nanyu Mineral Products Processing Plant; polystyrene, grade 622P, manufactured by Shanghai SECCO; and tin-plated copper wire, 0.5mm in diameter, manufactured by Shenzhen Caixin Copper and Aluminum Metal Materials Co., Ltd.

[0031] Example 1

[0032] A 1kV cross-linked polyethylene insulated cable is composed of a cable core, a shielding layer, a ceramic membrane, a sheath, and armor from the inside out. The cable core is obtained by extruding cross-linked polyethylene material onto the outside of the conductor to obtain the conductor core, and then stranding the conductor core. The ceramic membrane is made of halloysite nanotubes. The sheath is obtained by extruding cross-linked polyethylene material onto the outside of the ceramic membrane. The cross-linked polyethylene material is obtained by melt blending, fluorination, adding a cross-linking agent, and mixing of polyethylene, calcium oxide-doped boron nitride aerogel, and modified basalt fiber as raw materials. The modified basalt fiber is obtained by first surface modification of basalt fiber with nano-silica to obtain pretreated fiber, and then organic modification with polyethylene.

[0033] The conductor is made by first forming a single fiber core from an oxygen-free copper rod with a copper content of 99 wt.% or higher, and then twisting six fiber cores together.

[0034] The shielding layer is made by braiding tin-plated copper wires on the outside of the cable core; the ceramic film is tightly attached to the surface of the shielding layer and completely wraps it; the armor is made by wrapping steel strips around the outside of the sheath.

[0035] The ceramic membrane was prepared by the following method: First, 1 kg of halloysite nanotubes were added to 6 kg of anhydrous ethanol and stirred until homogeneous. Then, 0.1 kg of triethoxyoctylsilane was added and stirred until homogeneous. The mixture was stirred at 100°C for 5 h, and the precipitate was collected by centrifugation to obtain modified halloysite nanotubes. Next, the modified halloysite nanotubes were ultrasonically dispersed in 6 kg of organic solvent, and 3 kg of polystyrene was added. The mixture was then ultrasonically dispersed until homogeneous to obtain a spinning solution. Electrospinning and sintering were then performed to obtain the ceramic membrane. The organic solvent was prepared by mixing N,N-dimethylformamide and tetrahydrofuran in equal masses.

[0036] The electrospinning conditions were as follows: voltage 5kV, needle inner diameter 0.3mm, spinning solution pumping speed 50μL / min, distance between needle and collecting roller 8cm, collecting roller diameter 10cm, and rotation speed 2000r / min.

[0037] The sintering conditions are: heating to 900℃ at 15℃ / min and holding for sintering for 5 hours.

[0038] Calcium oxide-doped boron nitride aerogel was prepared by the following method: First, 4 kg of calcium nitrate, 1 kg of sodium silicate, and 1.5 kg of triethylamine were dissolved in 5 kg of 70% ethanol solution by stirring. The solution was heated to reflux and stirred for 30 minutes to obtain a calcium silicate solution. Then, 1 kg of boric acid and 1 kg of melamine were added to 5 kg of acetone and stirred at 60°C until transparent to obtain a boron nitride precursor solution. Finally, the calcium silicate solution was added to the boron nitride precursor solution, and the mixture was allowed to stand at -20°C for 12 hours, then supercritically dried and calcined at 400°C for 10 hours in air to obtain the final product.

[0039] In preparing cross-linked polyethylene materials, the mass ratio of polyethylene, calcium oxide-doped boron nitride aerogel, modified basalt fiber, and cross-linking agent is 10:0.7:0.5:0.3; the cross-linking agent is dicumyl peroxide.

[0040] Melt blending was performed using a torque rheometer under the following conditions: temperature 135℃, rotation speed 40 rpm, and time 30 minutes.

[0041] Fluorination treatment involves transferring the molten blended product into a sealed space containing fluorine gas and allowing it to stand for 8 hours under a 2T magnetic field. The gas in the sealed space consists of air and fluorine gas, with fluorine gas accounting for 3% of the volume.

[0042] The mixture was mixed using an open mill at a temperature of 120°C for 8 minutes.

[0043] The specific method for surface modification of basalt fibers using nano-silica is as follows: First, basalt fibers are immersed in a 3 mol / L hydrochloric acid solution with 10 times their weight, and treated with ultrasonic vibration at 400W for 50 minutes at 60℃. After filtration, the fibers are washed with water until neutral and dried to obtain acid-treated basalt fibers. Then, nano-silica is ultrasonically dispersed in a 85% ethanol solution with a volume concentration of 10 times its weight to obtain a nano-silica dispersion. Next, γ-aminopropyltriethoxysilane is added to a 85% ethanol solution with a volume concentration of 15 times its weight, and stirred for 1 hour. The nano-silica dispersion is then added, and stirring is continued for 1 hour. Finally, the acid-treated basalt fibers are added, and the mixture is stirred for 3 hours. The precipitate is collected by centrifugation, washed with water, and dried. The mass ratio of basalt fibers, nano-silica, and γ-aminopropyltriethoxysilane is 1:0.1:1.

[0044] The specific method for organic modification of basalt fiber using polyethylene is as follows: after mixing polyethylene and pretreated fiber at a mass ratio of 10:3, the mixture is extruded using a twin-screw extruder.

[0045] The temperatures in each zone of the twin-screw extruder are 160℃, 180℃, 210℃, and 170℃, respectively; the screw speed is 200 r / min.

[0046] Example 2

[0047] A 1kV cross-linked polyethylene insulated cable is composed of a cable core, a shielding layer, a ceramic membrane, a sheath, and armor from the inside out. The cable core is obtained by extruding cross-linked polyethylene material onto the outside of the conductor to obtain the conductor core, and then stranding the conductor core. The ceramic membrane is made of halloysite nanotubes. The sheath is obtained by extruding cross-linked polyethylene material onto the outside of the ceramic membrane. The cross-linked polyethylene material is obtained by melt blending, fluorination, adding a cross-linking agent, and mixing of polyethylene, calcium oxide-doped boron nitride aerogel, and modified basalt fiber as raw materials. The modified basalt fiber is obtained by first surface modification of basalt fiber with nano-silica to obtain pretreated fiber, and then organic modification with polyethylene.

[0048] The conductor is made by first forming a single fiber core from an oxygen-free copper rod with a copper content of 99 wt.% or higher, and then twisting six fiber cores together.

[0049] The shielding layer is made by braiding tin-plated copper wires on the outside of the cable core; the ceramic film is tightly attached to the surface of the shielding layer and completely wraps it; the armor is made by wrapping steel strips around the outside of the sheath.

[0050] The ceramic membrane was prepared by the following method: First, 1 kg of halloysite nanotubes were added to 8 kg of anhydrous ethanol and stirred until homogeneous. Then, 0.2 kg of triethoxyoctylsilane was added and stirred until homogeneous. The mixture was stirred at 120 °C for 6 h, and the precipitate was collected by centrifugation to obtain modified halloysite nanotubes. Next, the modified halloysite nanotubes were ultrasonically dispersed in 8 kg of organic solvent, and 4 kg of polystyrene was added. The mixture was then ultrasonically dispersed until homogeneous to obtain a spinning solution. Electrospinning and sintering were then performed to obtain the ceramic membrane. The organic solvent was prepared by mixing N,N-dimethylformamide and tetrahydrofuran in equal masses.

[0051] The electrospinning conditions were as follows: voltage 7kV, needle inner diameter 0.5mm, spinning solution pumping speed 60μL / min, distance between needle and collecting roller 10cm, collecting roller diameter 12cm, and rotation speed 3000r / min.

[0052] The sintering conditions were: heating to 950℃ at 20℃ / min and holding for 7 hours.

[0053] Calcium oxide-doped boron nitride aerogel was prepared by the following method: First, 4 kg of calcium nitrate, 1 kg of sodium silicate, and 1.5 kg of triethylamine were dissolved in 7 kg of 80% ethanol solution and heated to reflux. The solution was then stirred at this temperature for 40 minutes to obtain a calcium silicate solution. Next, 1 kg of boric acid and 1 kg of melamine were added to 7 kg of acetone and stirred at 70°C until transparent to obtain a boron nitride precursor solution. Finally, the calcium silicate solution was added to the boron nitride precursor solution, and the mixture was allowed to stand at -30°C for 15 hours. After supercritical drying, the mixture was calcined at 500°C for 12 hours in air to obtain the final product.

[0054] In preparing cross-linked polyethylene materials, the mass ratio of polyethylene, calcium oxide-doped boron nitride aerogel, modified basalt fiber, and cross-linking agent is 10:0.9:0.7:0.4; the cross-linking agent is dicumyl peroxide.

[0055] Melt blending was performed using a torque rheometer under the following conditions: temperature 145℃, rotation speed 50 rpm, and time 40 minutes.

[0056] Fluorination treatment involves transferring the molten blended product into a sealed space containing fluorine gas and allowing it to stand for 10 hours under a 3T magnetic field. The gas in the sealed space consists of air and fluorine gas, with fluorine gas accounting for 5% of the volume.

[0057] The mixture was mixed using an open mill at a temperature of 130°C for 10 minutes.

[0058] The specific method for surface modification of basalt fibers using nano-silica in the preparation of modified basalt fibers is as follows: First, basalt fibers are immersed in a 5 mol / L hydrochloric acid solution with 12 times their weight, and treated with ultrasonic vibration at 500W for 60 minutes at 70℃. After filtration, the fibers are washed with water until neutral and dried to obtain acid-treated basalt fibers. Then, nano-silica is ultrasonically dispersed in a 90% ethanol solution with a volume concentration of 12 times its weight to obtain a nano-silica dispersion. Next, γ-aminopropyltriethoxysilane is added to a 90% ethanol solution with a volume concentration of 20 times its weight, and stirred for 2 hours. The nano-silica dispersion is then added, and stirring is continued for 2 hours. Finally, the acid-treated basalt fibers are added, and the mixture is stirred for 4 hours. The precipitate is collected by centrifugation, washed with water, and dried. The mass ratio of basalt fibers, nano-silica, and γ-aminopropyltriethoxysilane is 1:0.2:2.

[0059] The specific method for organic modification of basalt fiber using polyethylene is as follows: after mixing polyethylene and pretreated fiber at a mass ratio of 10:5, the mixture is extruded using a twin-screw extruder.

[0060] The temperatures in each zone of the twin-screw extruder are 170℃, 190℃, 220℃, and 180℃, respectively; the screw speed is 250 r / min.

[0061] Example 3

[0062] A 1kV cross-linked polyethylene insulated cable is composed of a cable core, a shielding layer, a ceramic membrane, a sheath, and armor from the inside out. The cable core is obtained by extruding cross-linked polyethylene material onto the outside of the conductor to obtain the conductor core, and then stranding the conductor core. The ceramic membrane is made of halloysite nanotubes. The sheath is obtained by extruding cross-linked polyethylene material onto the outside of the ceramic membrane. The cross-linked polyethylene material is obtained by melt blending, fluorination, adding a cross-linking agent, and mixing of polyethylene, calcium oxide-doped boron nitride aerogel, and modified basalt fiber as raw materials. The modified basalt fiber is obtained by first surface modification of basalt fiber with nano-silica to obtain pretreated fiber, and then organic modification with polyethylene.

[0063] The conductor is made by first forming a single fiber core from an oxygen-free copper rod with a copper content of 99 wt.% or higher, and then twisting six fiber cores together.

[0064] The shielding layer is made by braiding tin-plated copper wires on the outside of the cable core; the ceramic film is tightly attached to the surface of the shielding layer and completely wraps it; the armor is made by wrapping steel strips around the outside of the sheath.

[0065] The ceramic membrane was prepared by the following method: First, 1 kg of halloysite nanotubes were added to 6 kg of anhydrous ethanol and stirred until homogeneous. Then, 0.2 kg of triethoxyoctylsilane was added and stirred until homogeneous. The mixture was stirred at 100°C for 6 hours, and the precipitate was collected by centrifugation to obtain modified halloysite nanotubes. Next, the modified halloysite nanotubes were ultrasonically dispersed in 6 kg of organic solvent, and 4 kg of polystyrene was added. The mixture was then ultrasonically dispersed until homogeneous to obtain a spinning solution. Electrospinning and sintering were then performed to obtain the ceramic membrane. The organic solvent was prepared by mixing N,N-dimethylformamide and tetrahydrofuran in equal masses.

[0066] The electrospinning conditions were as follows: voltage 5kV, needle inner diameter 0.5mm, spinning solution pumping speed 50μL / min, distance between needle and collecting roller 10cm, collecting roller diameter 10cm, and rotation speed 3000r / min.

[0067] The sintering conditions are: heating to 950℃ at 15℃ / min and holding for sintering for 5 hours.

[0068] Calcium oxide-doped boron nitride aerogel was prepared by the following method: First, 4 kg of calcium nitrate, 1 kg of sodium silicate, and 1.5 kg of triethylamine were dissolved in 7 kg of 70% ethanol solution and heated to reflux. The solution was then stirred at this temperature for 40 minutes to obtain a calcium silicate solution. Next, 1 kg of boric acid and 1 kg of melamine were added to 5 kg of acetone and stirred at 70°C until transparent to obtain a boron nitride precursor solution. Finally, the calcium silicate solution was added to the boron nitride precursor solution, and the mixture was allowed to stand at -20°C for 15 hours. After supercritical drying, the mixture was calcined at 400°C for 12 hours in air to obtain the final product.

[0069] In preparing cross-linked polyethylene materials, the mass ratio of polyethylene, calcium oxide-doped boron nitride aerogel, modified basalt fiber, and cross-linking agent is 10:0.7:0.7:0.3; the cross-linking agent is dicumyl peroxide.

[0070] Melt blending was performed using a torque rheometer under the following conditions: temperature 145℃, rotation speed 40 rpm, and time 40 minutes.

[0071] Fluorination treatment involves transferring the molten blended product into a sealed space containing fluorine gas and allowing it to stand for 10 hours under a 2T magnetic field. The gas in the sealed space consists of air and fluorine gas, with fluorine gas accounting for 3% of the volume.

[0072] The mixture was mixed using an open mill at a temperature of 130°C for 8 minutes.

[0073] The specific method for surface modification of basalt fibers using nano-silica is as follows: First, basalt fibers are immersed in a 3 mol / L hydrochloric acid solution with 12 times their weight, and treated with ultrasonic vibration at 400W for 60 minutes at 70℃. After filtration, the fibers are washed with water until neutral and dried to obtain acid-treated basalt fibers. Then, nano-silica is ultrasonically dispersed in a 90% ethanol solution with a volume concentration of 10 times its weight to obtain a nano-silica dispersion. Next, γ-aminopropyltriethoxysilane is added to a 90% ethanol solution with a volume concentration of 15 times its weight, and stirred for 1 hour. The nano-silica dispersion is then added, and stirring continues for 2 hours. Finally, the acid-treated basalt fibers are added, and the mixture is stirred for 3 hours. The precipitate is collected by centrifugation, washed with water, and dried. The mass ratio of basalt fibers, nano-silica, and γ-aminopropyltriethoxysilane is 1:0.2:1.

[0074] The specific method for organic modification of basalt fiber using polyethylene is as follows: after mixing polyethylene and pretreated fiber at a mass ratio of 10:5, the mixture is extruded using a twin-screw extruder.

[0075] The temperatures in each zone of the twin-screw extruder are 160℃, 190℃, 210℃, and 180℃, respectively; the screw speed is 200 r / min.

[0076] Example 4

[0077] A 1kV cross-linked polyethylene insulated cable is composed of a cable core, a shielding layer, a ceramic membrane, a sheath, and armor from the inside out. The cable core is obtained by extruding cross-linked polyethylene material onto the outside of the conductor to obtain the conductor core, and then stranding the conductor core. The ceramic membrane is made of halloysite nanotubes. The sheath is obtained by extruding cross-linked polyethylene material onto the outside of the ceramic membrane. The cross-linked polyethylene material is obtained by melt blending, fluorination, adding a cross-linking agent, and mixing of polyethylene, calcium oxide-doped boron nitride aerogel, and modified basalt fiber as raw materials. The modified basalt fiber is obtained by first surface modification of basalt fiber with nano-silica to obtain pretreated fiber, and then organic modification with polyethylene.

[0078] The conductor is made by first forming a single fiber core from an oxygen-free copper rod with a copper content of 99 wt.% or higher, and then twisting six fiber cores together.

[0079] The shielding layer is made by braiding tin-plated copper wires on the outside of the cable core; the ceramic film is tightly attached to the surface of the shielding layer and completely wraps it; the armor is made by wrapping steel strips around the outside of the sheath.

[0080] The ceramic membrane was prepared by the following method: First, 1 kg of halloysite nanotubes were added to 7 kg of anhydrous ethanol and stirred until homogeneous. Then, 0.15 kg of triethoxyoctylsilane was added and stirred until homogeneous. The mixture was stirred at 110 °C for 5 h, and the precipitate was collected by centrifugation to obtain modified halloysite nanotubes. Next, the modified halloysite nanotubes were ultrasonically dispersed in 7 kg of organic solvent, and 3.5 kg of polystyrene was added. The mixture was then ultrasonically dispersed until homogeneous to obtain a spinning solution. Electrospinning and sintering were then performed to obtain the ceramic membrane. The organic solvent was prepared by mixing N,N-dimethylformamide and tetrahydrofuran in equal masses.

[0081] The electrospinning conditions were as follows: voltage 6kV, needle inner diameter 0.4mm, spinning solution pumping speed 55μL / min, distance between needle and collecting roller 9cm, collecting roller diameter 11cm, and rotation speed 2500r / min.

[0082] The sintering conditions were: heating to 930℃ at 18℃ / min and holding for 6 hours.

[0083] Calcium oxide-doped boron nitride aerogel was prepared by the following method: First, 4 kg of calcium nitrate, 1 kg of sodium silicate, and 1.5 kg of triethylamine were dissolved in 6 kg of 75% ethanol solution by stirring. The solution was heated to reflux and stirred for 35 minutes to obtain a calcium silicate solution. Then, 1 kg of boric acid and 1 kg of melamine were added to 6 kg of acetone and stirred at 65°C until transparent to obtain a boron nitride precursor solution. Finally, the calcium silicate solution was added to the boron nitride precursor solution, and the mixture was allowed to stand at -25°C for 13 hours, then supercritically dried and calcined at 450°C for 11 hours in air to obtain the final product.

[0084] In preparing cross-linked polyethylene materials, the mass ratio of polyethylene, calcium oxide-doped boron nitride aerogel, modified basalt fiber, and cross-linking agent is 10:0.8:0.6:0.35; the cross-linking agent is dicumyl peroxide.

[0085] Melt blending was performed using a torque rheometer under the following conditions: temperature 140℃, rotation speed 45 rpm, and time 35 minutes.

[0086] Fluorination treatment involves transferring the molten blended product into a sealed space containing fluorine gas and allowing it to stand for 9 hours under a 2T magnetic field. The gas in the sealed space consists of air and fluorine gas, with fluorine gas accounting for 4% of the volume.

[0087] The mixing was carried out using an open mill at a temperature of 125°C for 9 minutes.

[0088] The specific method for surface modification of basalt fibers using nano-silica in the preparation of modified basalt fibers is as follows: First, basalt fibers are immersed in 11 times their weight of a 4 mol / L hydrochloric acid solution, treated with ultrasonic vibration at 500W for 55 minutes at 65℃, filtered, washed with water until neutral, and dried to obtain acid-treated basalt fibers; then, nano-silica is ultrasonically dispersed in 11 times its weight of a volume-concentration 88% ethanol solution to obtain a nano-silica dispersion; then, γ-aminopropyltriethoxysilane is added to 18 times its weight of a volume-concentration 88% ethanol solution, stirred for 1.5 h, the nano-silica dispersion is added, and stirring is continued for 1.5 h; finally, the acid-treated basalt fibers are added, stirred for 3.5 h, centrifuged to collect the precipitate, washed with water, and dried; wherein, the mass ratio of basalt fibers, nano-silica, and γ-aminopropyltriethoxysilane is 1:0.15:1.5.

[0089] The specific method for organic modification of basalt fiber using polyethylene is as follows: after mixing polyethylene and pretreated fiber at a mass ratio of 10:4, the mixture is extruded using a twin-screw extruder.

[0090] The temperatures in each zone of the twin-screw extruder are 165℃, 185℃, 215℃, and 175℃, respectively; the screw speed is 220 r / min.

[0091] Comparative Example 1

[0092] A 1kV cross-linked polyethylene insulated cable is composed of a cable core, a shielding layer, a sheath, and armor from the inside out. The cable core is obtained by extruding cross-linked polyethylene material onto the outside of the conductor to obtain the conductor core, and then stranding the conductor core. The sheath is obtained by extruding cross-linked polyethylene material onto the outside of the shielding layer. The cross-linked polyethylene material is obtained by melt blending, fluorination, adding a cross-linking agent, and mixing of polyethylene, calcium oxide, boron nitride aerogel, and modified basalt fiber as raw materials. The modified basalt fiber is obtained by first surface modification of basalt fiber with nano-silica to obtain pretreated fiber, and then organic modification with polyethylene.

[0093] The conductor is made by first forming a single fiber core from an oxygen-free copper rod with a copper content of 99 wt.% or higher, and then twisting six fiber cores together.

[0094] The shielding layer is made by braiding tin-plated copper wires on the outside of the cable core; the armor is made by wrapping steel strips around the outside of the sheath.

[0095] Calcium oxide-doped boron nitride aerogel was prepared by the following method: First, 4 kg of calcium nitrate, 1 kg of sodium silicate, and 1.5 kg of triethylamine were dissolved in 5 kg of 70% ethanol solution by stirring. The solution was heated to reflux and stirred for 30 minutes to obtain a calcium silicate solution. Then, 1 kg of boric acid and 1 kg of melamine were added to 5 kg of acetone and stirred at 60°C until transparent to obtain a boron nitride precursor solution. Finally, the calcium silicate solution was added to the boron nitride precursor solution, and the mixture was allowed to stand at -20°C for 12 hours, then supercritically dried and calcined at 400°C for 10 hours in air to obtain the final product.

[0096] In preparing cross-linked polyethylene materials, the mass ratio of polyethylene, calcium oxide-doped boron nitride aerogel, modified basalt fiber, and cross-linking agent is 10:0.7:0.5:0.3; the cross-linking agent is dicumyl peroxide.

[0097] Melt blending was performed using a torque rheometer under the following conditions: temperature 135℃, rotation speed 40 rpm, and time 30 minutes.

[0098] Fluorination treatment involves transferring the molten blended product into a sealed space containing fluorine gas and allowing it to stand for 8 hours under a 2T magnetic field. The gas in the sealed space consists of air and fluorine gas, with fluorine gas accounting for 3% of the volume.

[0099] The mixture was mixed using an open mill at a temperature of 120°C for 8 minutes.

[0100] The specific method for surface modification of basalt fibers using nano-silica is as follows: First, basalt fibers are immersed in a 3 mol / L hydrochloric acid solution with 10 times their weight, and treated with ultrasonic vibration at 400W for 50 minutes at 60℃. After filtration, the fibers are washed with water until neutral and dried to obtain acid-treated basalt fibers. Then, nano-silica is ultrasonically dispersed in a 85% ethanol solution with a volume concentration of 10 times its weight to obtain a nano-silica dispersion. Next, γ-aminopropyltriethoxysilane is added to a 85% ethanol solution with a volume concentration of 15 times its weight, and stirred for 1 hour. The nano-silica dispersion is then added, and stirring is continued for 1 hour. Finally, the acid-treated basalt fibers are added, and the mixture is stirred for 3 hours. The precipitate is collected by centrifugation, washed with water, and dried. The mass ratio of basalt fibers, nano-silica, and γ-aminopropyltriethoxysilane is 1:0.1:1.

[0101] The specific method for organic modification of basalt fiber using polyethylene is as follows: after mixing polyethylene and pretreated fiber at a mass ratio of 10:3, the mixture is extruded using a twin-screw extruder.

[0102] The temperatures in each zone of the twin-screw extruder are 160℃, 180℃, 210℃, and 170℃, respectively; the screw speed is 200 r / min.

[0103] Comparative Example 2

[0104] A 1kV cross-linked polyethylene insulated cable is composed of a cable core, a shielding layer, a ceramic membrane, a sheath, and armor from the inside out. The cable core is obtained by extruding cross-linked polyethylene material onto the outside of the conductor to obtain the conductor core, and then stranding the conductor core. The ceramic membrane is made of halloysite nanotubes. The sheath is obtained by extruding cross-linked polyethylene material onto the outside of the ceramic membrane. The cross-linked polyethylene material is obtained by melt blending polyethylene and modified basalt fiber as raw materials, fluorinating, adding a cross-linking agent, and mixing. The modified basalt fiber is obtained by first surface modification of basalt fiber with nano-silica to obtain pretreated fiber, and then organic modification with polyethylene.

[0105] The conductor is made by first forming a single fiber core from an oxygen-free copper rod with a copper content of 99 wt.% or higher, and then twisting six fiber cores together.

[0106] The shielding layer is made by braiding tin-plated copper wires on the outside of the cable core; the ceramic film is tightly attached to the surface of the shielding layer and completely wraps it; the armor is made by wrapping steel strips around the outside of the sheath.

[0107] The ceramic membrane was prepared by the following method: First, 1 kg of halloysite nanotubes were added to 6 kg of anhydrous ethanol and stirred until homogeneous. Then, 0.1 kg of triethoxyoctylsilane was added and stirred until homogeneous. The mixture was stirred at 100°C for 5 h, and the precipitate was collected by centrifugation to obtain modified halloysite nanotubes. Next, the modified halloysite nanotubes were ultrasonically dispersed in 6 kg of organic solvent, and 3 kg of polystyrene was added. The mixture was then ultrasonically dispersed until homogeneous to obtain a spinning solution. Electrospinning and sintering were then performed to obtain the ceramic membrane. The organic solvent was prepared by mixing N,N-dimethylformamide and tetrahydrofuran in equal masses.

[0108] The electrospinning conditions were as follows: voltage 5kV, needle inner diameter 0.3mm, spinning solution pumping speed 50μL / min, distance between needle and collecting roller 8cm, collecting roller diameter 10cm, and rotation speed 2000r / min.

[0109] The sintering conditions are: heating to 900℃ at 15℃ / min and holding for sintering for 5 hours.

[0110] In preparing cross-linked polyethylene materials, the mass ratio of polyethylene, modified basalt fiber, and cross-linking agent is 10:0.5:0.3; the cross-linking agent is dicumyl peroxide.

[0111] Melt blending was performed using a torque rheometer under the following conditions: temperature 135℃, rotation speed 40 rpm, and time 30 minutes.

[0112] Fluorination treatment involves transferring the molten blended product into a sealed space containing fluorine gas and allowing it to stand for 8 hours under a 2T magnetic field. The gas in the sealed space consists of air and fluorine gas, with fluorine gas accounting for 3% of the volume.

[0113] The mixture was mixed using an open mill at a temperature of 120°C for 8 minutes.

[0114] The specific method for surface modification of basalt fibers using nano-silica is as follows: First, basalt fibers are immersed in a 3 mol / L hydrochloric acid solution with 10 times their weight, and treated with ultrasonic vibration at 400W for 50 minutes at 60℃. After filtration, the fibers are washed with water until neutral and dried to obtain acid-treated basalt fibers. Then, nano-silica is ultrasonically dispersed in a 85% ethanol solution with a volume concentration of 10 times its weight to obtain a nano-silica dispersion. Next, γ-aminopropyltriethoxysilane is added to a 85% ethanol solution with a volume concentration of 15 times its weight, and stirred for 1 hour. The nano-silica dispersion is then added, and stirring is continued for 1 hour. Finally, the acid-treated basalt fibers are added, and the mixture is stirred for 3 hours. The precipitate is collected by centrifugation, washed with water, and dried. The mass ratio of basalt fibers, nano-silica, and γ-aminopropyltriethoxysilane is 1:0.1:1.

[0115] The specific method for organic modification of basalt fiber using polyethylene is as follows: after mixing polyethylene and pretreated fiber at a mass ratio of 10:3, the mixture is extruded using a twin-screw extruder.

[0116] The temperatures in each zone of the twin-screw extruder are 160℃, 180℃, 210℃, and 170℃, respectively; the screw speed is 200 r / min.

[0117] Comparative Example 3

[0118] A 1kV cross-linked polyethylene insulated cable is composed of a cable core, a shielding layer, a ceramic membrane, a sheath, and armor from the inside out. The cable core is obtained by extruding cross-linked polyethylene material onto the outside of the conductor to obtain the conductor core, and then stranding the conductor core. The ceramic membrane is made of halloysite nanotubes. The sheath is obtained by extruding cross-linked polyethylene material onto the outside of the ceramic membrane. The cross-linked polyethylene material is obtained by melt blending polyethylene and calcium oxide-doped boron nitride aerogel as raw materials, followed by fluorination treatment, addition of a cross-linking agent, and compounding.

[0119] The conductor is made by first forming a single fiber core from an oxygen-free copper rod with a copper content of 99 wt.% or higher, and then twisting six fiber cores together.

[0120] The shielding layer is made by braiding tin-plated copper wires on the outside of the cable core; the ceramic film is tightly attached to the surface of the shielding layer and completely wraps it; the armor is made by wrapping steel strips around the outside of the sheath.

[0121] The ceramic membrane was prepared by the following method: First, 1 kg of halloysite nanotubes were added to 6 kg of anhydrous ethanol and stirred until homogeneous. Then, 0.1 kg of triethoxyoctylsilane was added and stirred until homogeneous. The mixture was stirred at 100°C for 5 h, and the precipitate was collected by centrifugation to obtain modified halloysite nanotubes. Next, the modified halloysite nanotubes were ultrasonically dispersed in 6 kg of organic solvent, and 3 kg of polystyrene was added. The mixture was then ultrasonically dispersed until homogeneous to obtain a spinning solution. Electrospinning and sintering were then performed to obtain the ceramic membrane. The organic solvent was prepared by mixing N,N-dimethylformamide and tetrahydrofuran in equal masses.

[0122] The electrospinning conditions were as follows: voltage 5kV, needle inner diameter 0.3mm, spinning solution pumping speed 50μL / min, distance between needle and collecting roller 8cm, collecting roller diameter 10cm, and rotation speed 2000r / min.

[0123] The sintering conditions are: heating to 900℃ at 15℃ / min and holding for sintering for 5 hours.

[0124] Calcium oxide-doped boron nitride aerogel was prepared by the following method: First, 4 kg of calcium nitrate, 1 kg of sodium silicate, and 1.5 kg of triethylamine were dissolved in 5 kg of 70% ethanol solution by stirring. The solution was heated to reflux and stirred for 30 minutes to obtain a calcium silicate solution. Then, 1 kg of boric acid and 1 kg of melamine were added to 5 kg of acetone and stirred at 60°C until transparent to obtain a boron nitride precursor solution. Finally, the calcium silicate solution was added to the boron nitride precursor solution, and the mixture was allowed to stand at -20°C for 12 hours, then supercritically dried and calcined at 400°C for 10 hours in air to obtain the final product.

[0125] In preparing cross-linked polyethylene materials, the mass ratio of polyethylene, calcium oxide-doped boron nitride aerogel, and cross-linking agent is 10:0.7:0.3; the cross-linking agent is dicumyl peroxide.

[0126] Melt blending was performed using a torque rheometer under the following conditions: temperature 135℃, rotation speed 40 rpm, and time 30 minutes.

[0127] Fluorination treatment involves transferring the molten blended product into a sealed space containing fluorine gas and allowing it to stand for 8 hours under a 2T magnetic field. The gas in the sealed space consists of air and fluorine gas, with fluorine gas accounting for 3% of the volume.

[0128] The mixture was mixed using an open mill at a temperature of 120°C for 8 minutes.

[0129] Comparative Example 4

[0130] A 1kV cross-linked polyethylene insulated cable is composed of a cable core, a shielding layer, a ceramic membrane, a sheath, and armor from the inside out. The cable core is obtained by extruding cross-linked polyethylene material onto the outside of a conductor, and then stranding the conductor core. The ceramic membrane is made of halloysite nanotubes. The sheath is obtained by extruding cross-linked polyethylene material onto the outside of the ceramic membrane. The cross-linked polyethylene material is obtained by melt blending, fluorination, adding a cross-linking agent, and mixing of polyethylene, calcium oxide-doped boron nitride aerogel, and modified basalt fiber as raw materials. The modified basalt fiber is obtained by organically modifying basalt fiber.

[0131] The conductor is made by first forming a single fiber core from an oxygen-free copper rod with a copper content of 99 wt.% or higher, and then twisting six fiber cores together.

[0132] The shielding layer is made by braiding tin-plated copper wires on the outside of the cable core; the ceramic film is tightly attached to the surface of the shielding layer and completely wraps it; the armor is made by wrapping steel strips around the outside of the sheath.

[0133] The ceramic membrane was prepared by the following method: First, 1 kg of halloysite nanotubes were added to 6 kg of anhydrous ethanol and stirred until homogeneous. Then, 0.1 kg of triethoxyoctylsilane was added and stirred until homogeneous. The mixture was stirred at 100°C for 5 h, and the precipitate was collected by centrifugation to obtain modified halloysite nanotubes. Next, the modified halloysite nanotubes were ultrasonically dispersed in 6 kg of organic solvent, and 3 kg of polystyrene was added. The mixture was then ultrasonically dispersed until homogeneous to obtain a spinning solution. Electrospinning and sintering were then performed to obtain the ceramic membrane. The organic solvent was prepared by mixing N,N-dimethylformamide and tetrahydrofuran in equal masses.

[0134] The electrospinning conditions were as follows: voltage 5kV, needle inner diameter 0.3mm, spinning solution pumping speed 50μL / min, distance between needle and collecting roller 8cm, collecting roller diameter 10cm, and rotation speed 2000r / min.

[0135] The sintering conditions are: heating to 900℃ at 15℃ / min and holding for sintering for 5 hours.

[0136] Calcium oxide-doped boron nitride aerogel was prepared by the following method: First, 4 kg of calcium nitrate, 1 kg of sodium silicate, and 1.5 kg of triethylamine were dissolved in 5 kg of 70% ethanol solution by stirring. The solution was heated to reflux and stirred for 30 minutes to obtain a calcium silicate solution. Then, 1 kg of boric acid and 1 kg of melamine were added to 5 kg of acetone and stirred at 60°C until transparent to obtain a boron nitride precursor solution. Finally, the calcium silicate solution was added to the boron nitride precursor solution, and the mixture was allowed to stand at -20°C for 12 hours, then supercritically dried and calcined at 400°C for 10 hours in air to obtain the final product.

[0137] In preparing cross-linked polyethylene materials, the mass ratio of polyethylene, calcium oxide-doped boron nitride aerogel, modified basalt fiber, and cross-linking agent is 10:0.7:0.5:0.3; the cross-linking agent is dicumyl peroxide.

[0138] Melt blending was performed using a torque rheometer under the following conditions: temperature 135℃, rotation speed 40 rpm, and time 30 minutes.

[0139] Fluorination treatment involves transferring the molten blended product into a sealed space containing fluorine gas and allowing it to stand for 8 hours under a 2T magnetic field. The gas in the sealed space consists of air and fluorine gas, with fluorine gas accounting for 3% of the volume.

[0140] The mixture was mixed using an open mill at a temperature of 120°C for 8 minutes.

[0141] The specific method for organic modification of basalt fiber using polyethylene is as follows: after mixing polyethylene and basalt fiber evenly at a mass ratio of 10:3, the mixture can be extruded using a twin-screw extruder.

[0142] The temperatures in each zone of the twin-screw extruder are 160℃, 180℃, 210℃, and 170℃, respectively; the screw speed is 200 r / min.

[0143] Test case

[0144] The insulation and anti-aging properties of the cables obtained in Examples 1-4 and Comparative Examples 1-4 were investigated respectively.

[0145] 1. Volume resistivity test:

[0146] Under conditions of 25℃, a DC voltage is applied across both ends of the cable sheath, and the volume resistivity R is calculated using the following formula. h :

[0147] R h = V / I × S / L

[0148] Where V is the applied voltage, I is the steady-state current, S is the cross-sectional area, and L is the length.

[0149] 2. Anti-aging performance test:

[0150] Referring to ASTM D573, hot air aging was performed at 150℃ for 240 hours. Tensile strength was tested before and after aging (referencing GB / T2951.11-2008). The change rate of tensile strength (%) was calculated as: (Tensile strength after aging - Tensile strength before aging) / Tensile strength before aging × 100. The ceramic membrane and sheath are integrated; the ceramic membrane is not removed during sampling.

[0151] The test results are shown in Table 1.

[0152] Table 1. Cable Performance Evaluation

[0153]

[0154] As shown in Table 1, the cables obtained in Examples 1 to 4 have excellent insulation and anti-aging properties.

[0155] Comparative Example 1 omitted the ceramic membrane, Comparative Example 2 omitted the calcium oxide-doped boron nitride aerogel, Comparative Example 3 omitted the modified basalt fiber, and Comparative Example 4 omitted the nano-silica surface modification during the preparation of the modified basalt fiber. The insulation and anti-aging properties of all samples were significantly worse. This indicates that the support of the ceramic membrane and the addition of calcium oxide-doped boron nitride aerogel and modified basalt fiber during the preparation of the sheath are beneficial to the optimization of the microstructure and the improvement of insulation and anti-aging properties.

[0156] The present invention has been illustrated through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of individual raw materials in the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A 1kV cross-linked polyethylene insulated cable, characterized in that, From the inside out, it consists of a cable core, a shielding layer, a ceramic membrane, a sheath, and armor. The cable core is obtained by extruding cross-linked polyethylene material onto the outside of a conductor, and then stranding the conductor core together. The ceramic membrane is made of halloysite nanotubes. The sheath is obtained by extruding cross-linked polyethylene material onto the outside of a ceramic membrane. The cross-linked polyethylene material is obtained by melt blending, fluorination, adding a cross-linking agent, and kneading polyethylene, using polyethylene, calcium oxide-doped boron nitride aerogel, and modified basalt fiber as raw materials. The modified basalt fiber is obtained by first surface modification of basalt fiber with nano-silica to obtain pretreated fiber, and then organic modification with polyethylene. The calcium oxide-doped boron nitride aerogel, by weight, is prepared by the following method: First, 4 parts calcium nitrate, 1 part sodium silicate, and 1.5 parts triethylamine are dissolved in 5-7 parts of a 70-80% (v / v) ethanol solution, heated to reflux, and stirred for 30-40 minutes to obtain a calcium silicate solution. Then, 1 part boric acid and 1 part melamine are added to 5-7 parts acetone and stirred at 60-70°C until transparent to obtain a boron nitride precursor solution. Finally, the calcium silicate solution is added to the boron nitride precursor solution, and the mixture is allowed to stand at -20 to -30°C for 12-15 hours, supercritically dried, and calcined at 400-500°C for 10-12 hours in air to obtain the final product. In the preparation of cross-linked polyethylene material, the mass ratio of polyethylene, calcium oxide-doped boron nitride aerogel, modified basalt fiber, and cross-linking agent is 10:0.7-0.9:0.5-0.7:0.3-0.4; the cross-linking agent is dicumyl peroxide. The specific method for surface modification of basalt fibers using nano-silica in the preparation of modified basalt fibers is as follows: First, the basalt fibers are immersed in a 3-5 mol / L hydrochloric acid solution at 10-12 times their weight, and then ultrasonically treated at 400-500W for 50-60 minutes at 60-70℃. After filtration, the fibers are washed with water until neutral and dried to obtain acid-treated basalt fibers. Then, the nano-silica is ultrasonically dispersed in an 85-90% ethyl acetate solution at 10-12 times their weight. A nano-silica dispersion was obtained in an alcohol solution. Then, γ-aminopropyltriethoxysilane was added to an 85-90% ethanol solution with a volume concentration of 15-20 times its weight, and stirred for 1-2 hours. The nano-silica dispersion was then added, and stirring was continued for 1-2 hours. Finally, acid-treated basalt fibers were added, and stirring was carried out for 3-4 hours. The precipitate was collected by centrifugation, washed with water, and dried. The mass ratio of basalt fibers, nano-silica, and γ-aminopropyltriethoxysilane was 1:0.1-0.2:1-2.

2. A 1kV cross-linked polyethylene insulated cable according to claim 1, characterized in that, The conductor is made by first forming a single fiber core from an oxygen-free copper rod with a copper content of 99 wt.% or higher, and then twisting 6 to 8 fiber cores together.

3. A 1kV cross-linked polyethylene insulated cable according to claim 1, characterized in that, The shielding layer is formed by braiding tin-plated copper wires on the outside of the cable core; the ceramic film is tightly attached to the surface of the shielding layer and completely wraps it; the armor is formed by wrapping steel strip around the outside of the sheath.

4. A 1kV cross-linked polyethylene insulated cable according to claim 1, characterized in that, The ceramic membrane is prepared by the following method, by weight: 1 part halloysite nanotubes are added to 6-8 parts anhydrous ethanol and stirred until homogeneous. Then, 0.1-0.2 parts triethoxyoctylsilane are added and stirred until homogeneous. The mixture is stirred at 100-120°C for 5-6 hours, and the precipitate is collected by centrifugation to obtain modified halloysite nanotubes. The modified halloysite nanotubes are then ultrasonically dispersed in 6-8 parts organic solvent, and 3-4 parts polystyrene are added. The mixture is further ultrasonically dispersed until homogeneous to obtain a spinning solution. Electrospinning and sintering are then performed to obtain the ceramic membrane.

5. A 1kV cross-linked polyethylene insulated cable according to claim 1, characterized in that, Melt blending was performed using a torque rheometer under the following conditions: temperature 135–145°C, rotation speed 40–50 rpm, and time 30–40 minutes.

6. A 1kV cross-linked polyethylene insulated cable according to claim 1, characterized in that, Fluorination treatment involves transferring the melt-blended product into a sealed space containing fluorine gas and allowing it to stand for 8–10 hours under a magnetic field of 2–3T. The gas in the sealed space consists of air and fluorine gas, with fluorine gas accounting for 3–5% of the volume. Use an open mill for mixing, with a mixing temperature of 120-130℃ and a mixing time of 8-10 minutes.

7. A 1kV cross-linked polyethylene insulated cable according to claim 1, characterized in that, The specific method for organic modification of basalt fiber using polyethylene is as follows: after mixing polyethylene and pretreated fiber at a mass ratio of 10:3 to 5, the mixture is extruded using a twin-screw extruder.

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