High-temperature-resistant power cable

Abstract

The invention relates to the technical field of cable structure design, and discloses a high-temperature-resistant power cable which comprises the steps of conductor pretreatment, inner shielding layer preparation, main insulating layer construction, outer shielding layer forming, irradiation crosslinking and sheath extrusion. An interface air gap between a conductor and an insulating layer in a high-temperature environment is eliminated, the partial discharge risk caused by electric field distortion is avoided, a stable inner and outer double-layer electric field shielding mechanism is established, it is guaranteed that the cable keeps uniform electric field distribution under the wide-temperature-range working condition, and the technical defect that an electric field is unstable due to thermal expansion of a traditional cable is overcome; through the design of the main insulating layer synergistically enhanced by the functionalized ceramic microspheres and the irradiation-thermal stability synergistic crosslinking process, the high-temperature deformation resistance and molecular structure stability of the insulating material are synchronously improved, so that the cable still maintains stable dielectric properties and mechanical strength under extreme temperature conditions.

Description

Technical Field

[0001] This invention relates to the field of cable structure design technology, specifically to a high-temperature resistant power cable. Background Technology

[0002] High-temperature resistant wires and cables are special cables that can transmit signals or electrical energy stably for a long time in specific high-temperature environments. They are mainly used in aerospace, automobile manufacturing, industrial robots and 5G base stations. Their structure includes conductors, insulation layers and armor layers. Conductor types include single and multiple conductors. The insulation materials are high-temperature resistant composite materials such as irradiated cross-linked polyolefin, silicone rubber and fluororesin.

[0003] In the field of power transmission under high-temperature conditions, traditional cable structures have the following defects: insufficient bonding force between the conductor and the insulation layer; high-temperature thermal expansion leads to delamination and the formation of air gaps, inducing electric field distortion and partial discharge; conventional insulation materials undergo thermal degradation under long-term high-temperature conditions, and molecular chain breakage leads to irreversible reduction in insulation strength; the degree of cross-linking of organic insulation materials is difficult to improve to an ideal level, the temperature range tolerance of existing cross-linking processes is insufficient, and the cross-linked structure is prone to disintegration under high-temperature conditions; the conductive filler in the shielding layer has poor dispersion, and the permeation network becomes unstable during high-temperature operation, causing fluctuations in electric field shielding effectiveness; the sheath material has limited resistance to thermal deformation, and it is prone to softening and deformation under continuous high temperatures, losing its mechanical protection function; existing technologies have not solved the problem of synergistic improvement of the dielectric and thermal conductivity of the insulation layer, and local heat accumulation accelerates insulation aging.

[0004] Therefore, a high-temperature resistant power cable is proposed to solve the above problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-temperature resistant power cable, solving the problems mentioned in the background section.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-temperature resistant power cable, the cable comprising, from the inside out, sequentially covered with: Plasma-activated copper conductors; Inner shielding layer containing boron nitride nanoparticles: volume resistivity ≤10³Ω·m; Ceramic microsphere-reinforced main insulation layer: dielectric strength ≥35kV / mm; Graphene composite outer shielding layer: surface resistance ≤10 4 Ω; High temperature resistant sheath: Long-term operating temperature ≥200℃.

[0007] Preferably, it includes the following steps: Step 1: Conductor pretreatment. Annealed copper conductors are selected and plasma surface activation treatment is performed under inert gas protection. The activation power is 300-500W and the treatment time is 5-10 minutes. Step 2: Preparation of the inner shielding layer. Modified ethylene-vinyl acetate copolymer, nano boron nitride and silane coupling agent are mixed at a mass ratio of 100:15-20:0.5-1.5, melt-blended at 120-140℃ using a twin-screw extruder, and extruded to coat the surface of the pretreated conductor to form an inner shielding layer with a thickness of 0.3-0.5mm. Step 3: Construction of the main insulation layer. Cross-linked polyethylene, functionalized ceramic microspheres and antioxidants are placed in a mixer at a mass ratio of 100:25-35:1-3 and mixed at 150-170℃ for 20-30 minutes. The mixture is then coated onto the outside of the inner shielding layer through a three-layer co-extrusion device to form a main insulation layer with a thickness of 2.0-3.0 mm. Step 4: Forming the outer shielding layer. Conductive carbon black, graphene composite, vinyl elastomer and crosslinking agent are mixed in a mass ratio of 100:12-18:0.8-1.2 and coated onto the main insulating layer by extrusion coating, with a thickness of 0.4-0.6 mm. Step 5: Irradiation crosslinking. The cable is irradiated using an electron accelerator with an irradiation dose of 120-180 kGy and an energy of 2.5-3.5 MeV. Step 6: Sheath extrusion. Under an argon atmosphere, high-temperature resistant polytetrafluoroethylene propylene resin is extruded and coated onto the outermost layer of the cable to a thickness of 1.2-1.8 mm at an extrusion temperature of 280-320℃.

[0008] Preferably, the plasma surface activation treatment in step one specifically involves: placing a copper conductor in a vacuum chamber and evacuating it to a vacuum level of 5× -1× Argon gas was introduced to maintain the pressure at 20-50 Pa, and the plasma was excited using a radio frequency power supply with a frequency of 13.56 MHz.

[0009] Preferably, the modified ethylene-vinyl acetate copolymer is prepared by the following method: Ethylene-vinyl acetate copolymer (VA content 28-33wt%) is mixed with maleic anhydride graft at a mass ratio of 100:8-12 and reacted at 140-160℃ for 40-60 min, with nitrogen continuously purging during the reaction. VA is an abbreviation for vinyl acetate.

[0010] Preferably, the functionalized ceramic microspheres are prepared by the following steps: Ⅰ. Select hollow alumina microspheres with a particle size of 10-20 μm, and treat them under vacuum by introducing hexamethyldisilazane vapor at 20-30 sccm for 30-45 min; II. Immerse the microspheres treated in step a in an ethanol solution containing 0.5-1.0 wt% titanate and ultrasonically disperse for 15-25 min; III. Under nitrogen protection, heat treatment at 200-300℃ for 1-2 hours yields functionalized ceramic microspheres with a surface grafted siloxane-titanium ester composite layer.

[0011] Preferably, the amount of functionalized ceramic microspheres added to the main insulating layer raw material is 28-32 wt%, and the microspheres comprise: 80-85 wt% alumina matrix 8-12 wt% of surface-grafted siloxane layer Titanate catalyst layer 5-8 wt%.

[0012] Preferably, the conductive carbon black-graphene composite is prepared by the following method: Conductive carbon black with a particle size of 30-50 nm was mixed with graphene oxide at a mass ratio of 3:1-5:1 and added to an aqueous solution containing 0.1 mol / L ascorbic acid. The pH of the solution was controlled at ≤4. The mixture was reduced at 80-95℃ for 2-4 hours and then freeze-dried to obtain a three-dimensional interpenetrating network structure composite.

[0013] Preferably, the high-temperature resistant perfluoroethylene propylene resin comprises the following components: Tetrafluoroethylene-hexafluoropropylene copolymer matrix: 100 parts; Nano titanium dioxide: 5-8 parts; Perfluorosulfonic acid resin powder: 3-5 parts; Perfluoropolyether lubricant: 0.5-1.2 parts.

[0014] Preferably, the nano-titanium dioxide is pretreated with silane coupling agent KH-550, and the pretreatment method is as follows: Nano-titanium dioxide was dispersed in an ethanol solution containing 2-3 wt% KH-550, ultrasonicated for 30 min, and then dried at 110℃ for 2 h.

[0015] Preferably, step five, after irradiation crosslinking, further includes a heat stabilization treatment: Place the cable in a hot air circulation box at 180-200℃ for 4-6 hours, with a heating rate ≤5℃ / min.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. In this invention, the unique conductor interface activation treatment and composite shielding layer structure eliminate the interfacial air gap between the conductor and the insulation layer under high temperature conditions, avoid the risk of partial discharge caused by electric field distortion, and establish a stable inner and outer double-layer electric field shielding mechanism to ensure that the cable maintains a uniform electric field distribution under wide temperature range conditions, thus solving the technical defects of electric field instability caused by thermal expansion in traditional cables.

[0017] 2. In this invention, the main insulation layer design with functionalized ceramic microspheres is enhanced by synergistic reinforcement, and the irradiation-thermal stabilization synergistic crosslinking process is used to simultaneously improve the high-temperature deformation resistance and molecular structure stability of the insulation material. This overcomes the tendency of organic insulation materials to thermally degrade in high-temperature environments, enabling the cable to maintain stable dielectric properties and mechanical strength under extreme temperature conditions. This solves the technical contradiction that the thermal stability and electrical performance of traditional insulation materials are difficult to reconcile.

[0018] 3. In this invention, a three-dimensional interpenetrating outer shielding layer and a nano-reinforced sheath system constructed with composite conductive materials are used to achieve dynamic stability of the permeation network under high temperature conditions, avoid the attenuation of shielding effectiveness caused by thermal movement of conductive fillers, and at the same time give the sheath a long-lasting thermal protection function, ensuring that the cable as a whole maintains the integrity of the mechanical barrier and the reliability of electromagnetic shielding in a high-temperature environment for a long time. Attached Figure Description

[0019] Figure 1 This is a flowchart of a high-temperature resistant power cable according to the present invention. Detailed Implementation

[0020] 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1: A high-temperature resistant power cable, comprising, from the inside out, the following components: Plasma-activated copper conductors; Inner shielding layer containing boron nitride nanoparticles: volume resistivity ≤10³Ω·m; Ceramic microsphere-reinforced main insulation layer: dielectric strength ≥35kV / mm; Graphene composite outer shielding layer: surface resistance ≤10 4 Ω; High temperature resistant sheath: Long-term operating temperature ≥200℃.

[0022] Includes the following steps: Step 1: Conductor pretreatment. Annealed copper conductors are selected and subjected to plasma surface activation treatment under inert gas protection. The activation power is 300W and the treatment time is 5min. Step 2: Preparation of inner shielding layer. Modified ethylene-vinyl acetate copolymer, nano boron nitride and silane coupling agent are mixed at a mass ratio of 100:15:0.5, melt-blended at 120°C using a twin-screw extruder, and extruded to coat the surface of the pretreated conductor to form an inner shielding layer with a thickness of 0.3 mm. Step 3: Construction of the main insulation layer. Cross-linked polyethylene, functionalized ceramic microspheres and antioxidants are placed in a mixer at a mass ratio of 100:25:1 and mixed at 150°C for 20 minutes. The mixture is then coated onto the outside of the inner shielding layer through a three-layer co-extrusion device to form a main insulation layer with a thickness of 2.0 mm. Step 4: Forming the outer shielding layer. Conductive carbon black, graphene composite, vinyl elastomer and crosslinking agent are mixed in a mass ratio of 100:12:0.8 and coated onto the main insulating layer by extrusion coating, with a thickness of 0.4 mm. Step 5: Irradiation crosslinking. The cable is irradiated using an electron accelerator with an irradiation dose of 120 kGy and an energy of 2.5 MeV. Step Six: Sheath Extrusion. Under an argon atmosphere, high-temperature resistant polytetrafluoroethylene propylene resin is extruded and coated onto the outermost layer of the cable to a thickness of 1.2 mm at an extrusion temperature of 280℃.

[0023] The plasma surface activation treatment in step one specifically involves placing a copper conductor in a vacuum chamber and evacuating it to 5× Argon gas was introduced to maintain the pressure at 20 Pa, and the plasma was excited using a radio frequency power supply with a frequency of 13.56 MHz.

[0024] The modified ethylene-vinyl acetate copolymer was prepared by the following method: Ethylene-vinyl acetate copolymer (VA content 28wt%) was mixed with maleic anhydride graft at a mass ratio of 100:8 and reacted at 140℃ for 40 min, with nitrogen continuously purging during the reaction.

[0025] Functionalized ceramic microspheres are prepared through the following steps: Ⅰ. Select hollow alumina microspheres with a particle size of 10 μm, and treat them under vacuum by introducing hexamethyldisilazane vapor at 20 sccm for 30 min; II. The microspheres treated in step I were immersed in an ethanol solution containing 0.5 wt% titanate and ultrasonically dispersed for 15 min. III. Functionalized ceramic microspheres with surface grafted siloxane-titanium ester composite layer were obtained by heat treatment at 250℃ for 1 hour under nitrogen protection.

[0026] The amount of functionalized ceramic microspheres added to the main insulating layer raw material is 28 wt%, and the microspheres contain: 80wt% alumina matrix 12wt% of surface-grafted siloxane layer Titanate catalyst layer 8wt%.

[0027] The conductive carbon black-graphene composite was prepared by the following method: Conductive carbon black with a particle size of 30 nm was mixed with graphene oxide at a mass ratio of 3:1 and added to an aqueous solution containing 0.1 mol / L ascorbic acid. The pH of the solution was controlled at ≤4. The reaction was carried out at 80 °C for 2 h. After freeze drying, a three-dimensional interpenetrating network structure composite was obtained.

[0028] High-temperature resistant perfluoroethylene propylene resin contains the following components: Tetrafluoroethylene-hexafluoropropylene copolymer matrix: 100 parts; Nano titanium dioxide: 5 parts; Perfluorosulfonic acid resin powder: 3 parts; Perfluoropolyether lubricant: 0.5 parts.

[0029] Nano-titanium dioxide is pretreated with silane coupling agent KH-550. The pretreatment method is as follows: Nano-titanium dioxide was dispersed in an ethanol solution containing 2wt% KH-550, ultrasonicated for 30 min, and then dried at 110℃ for 2 h.

[0030] Step five, following irradiation crosslinking, also includes a heat stabilization treatment: The cable was placed in a 180℃ hot air circulation box for 4 hours, with a heating rate ≤5℃ / min.

[0031] Example 2: A high-temperature resistant power cable, comprising, from the inside out, the following components: Plasma-activated copper conductors; Inner shielding layer containing boron nitride nanoparticles: volume resistivity ≤10³Ω·m; Ceramic microsphere-reinforced main insulation layer: dielectric strength ≥35kV / mm; Graphene composite outer shielding layer: surface resistance ≤10 4 Ω; High temperature resistant sheath: Long-term operating temperature ≥200℃.

[0032] Includes the following steps: Step 1: Conductor pretreatment. Annealed copper conductors are selected and plasma surface activation treatment is performed under inert gas protection. The activation power is 400W and the treatment time is 8min. Step 2: Preparation of inner shielding layer. Modified ethylene-vinyl acetate copolymer, nano boron nitride and silane coupling agent are mixed at a mass ratio of 100:18:1.0, melt-blended at 130°C using a twin-screw extruder, and extruded to coat the surface of the pretreated conductor to form an inner shielding layer with a thickness of 0.4 mm. Step 3: Construction of the main insulation layer. Cross-linked polyethylene, functionalized ceramic microspheres and antioxidants are placed in a mixer at a mass ratio of 100:30:2 and mixed at 160°C for 25 minutes. The mixture is then coated onto the outside of the inner shielding layer through a three-layer co-extrusion device to form a main insulation layer with a thickness of 2.5 mm. Step 4: Forming the outer shielding layer. Conductive carbon black, graphene composite, vinyl elastomer and crosslinking agent are mixed in a mass ratio of 100:15:1.0 and coated onto the main insulating layer by extrusion coating, with a thickness of 0.5mm. Step 5: Irradiation crosslinking. The cable is irradiated using an electron accelerator with an irradiation dose of 150 kGy and an energy of 3.0 MeV. Step Six: Sheath Extrusion. Under an argon atmosphere, high-temperature resistant polytetrafluoroethylene propylene resin is extruded and coated onto the outermost layer of the cable to a thickness of 1.5 mm at an extrusion temperature of 300℃.

[0033] The plasma surface activation treatment in step one specifically involves placing a copper conductor in a vacuum chamber and evacuating it to a vacuum level of 1× Argon gas was introduced to maintain the pressure at 35 Pa, and the plasma was excited using a radio frequency power supply with a frequency of 13.56 MHz.

[0034] The modified ethylene-vinyl acetate copolymer was prepared by the following method: Ethylene-vinyl acetate copolymer (VA content 30wt%) was mixed with maleic anhydride graft at a mass ratio of 100:10 and reacted at 150℃ for 50 min, with nitrogen continuously purging during the reaction.

[0035] Functionalized ceramic microspheres are prepared through the following steps: I. Hollow alumina microspheres with a particle size of 15 μm were selected and hexamethyldisilazane vapor was introduced at 25 sccm under vacuum for 38 min. II. The microspheres treated in step I were immersed in an ethanol solution containing 0.8 wt% titanate and ultrasonically dispersed for 20 min; III. Functionalized ceramic microspheres with surface grafted siloxane-titanium ester composite layer were obtained by heat treatment at 250℃ for 1.5h under nitrogen protection.

[0036] The amount of functionalized ceramic microspheres added to the main insulating layer raw material is 30 wt%, and the microspheres contain: 83wt% alumina matrix 10wt% of surface-grafted siloxane layer 7 wt% titanate catalyst layer.

[0037] The conductive carbon black-graphene composite was prepared by the following method: Conductive carbon black with a particle size of 40 nm was mixed with graphene oxide at a mass ratio of 4:1 and added to an aqueous solution containing 0.1 mol / L ascorbic acid. The pH of the solution was controlled at ≤4. The reaction was carried out at 90 °C for 3 h. After freeze drying, a three-dimensional interpenetrating network structure composite was obtained.

[0038] High-temperature resistant perfluoroethylene propylene resin contains the following components: Tetrafluoroethylene-hexafluoropropylene copolymer matrix: 100 parts; Nano titanium dioxide: 7 parts; Perfluorosulfonic acid resin powder: 4 parts; Perfluoropolyether lubricant: 0.8 parts.

[0039] Nano-titanium dioxide is pretreated with silane coupling agent KH-550. The pretreatment method is as follows: Nano-titanium dioxide was dispersed in an ethanol solution containing 2.5 wt% KH-550, ultrasonicated for 30 min, and then dried at 110 °C for 2 h.

[0040] Step five, following irradiation crosslinking, also includes a heat stabilization treatment: The cable was placed in a 190℃ hot air circulation box for 5 hours, with a heating rate ≤5℃ / min.

[0041] Example 3: A high-temperature resistant power cable, comprising, from the inside out, the following components: Plasma-activated copper conductors; Inner shielding layer containing boron nitride nanoparticles: volume resistivity ≤10³Ω·m; Ceramic microsphere-reinforced main insulation layer: dielectric strength ≥35kV / mm; Graphene composite outer shielding layer: surface resistance ≤10 4 Ω; High temperature resistant sheath: Long-term operating temperature ≥200℃.

[0042] Includes the following steps: Step 1: Conductor pretreatment. Annealed copper conductors are selected and subjected to plasma surface activation treatment under inert gas protection. The activation power is 500W and the treatment time is 10min. Step 2: Preparation of inner shielding layer. Modified ethylene-vinyl acetate copolymer, nano boron nitride and silane coupling agent are mixed at a mass ratio of 100:20:1.5, melt-blended at 140°C using a twin-screw extruder, and extruded to coat the surface of the pretreated conductor to form an inner shielding layer with a thickness of 0.5 mm. Step 3: Construction of the main insulation layer. Cross-linked polyethylene, functionalized ceramic microspheres and antioxidants are placed in a mixer at a mass ratio of 100:35:3 and mixed at 170°C for 30 minutes. The mixture is then coated onto the outside of the inner shielding layer through a three-layer co-extrusion device to form a main insulation layer with a thickness of 3.0 mm. Step 4: Forming the outer shielding layer. Conductive carbon black, graphene composite, vinyl elastomer and crosslinking agent are mixed in a mass ratio of 100:18:1.2 and coated onto the main insulating layer by extrusion coating, with a thickness of 0.6 mm. Step 5: Irradiation crosslinking. The cable is irradiated using an electron accelerator with an irradiation dose of 180 kGy and an energy of 3.5 MeV. Step Six: Sheath Extrusion. Under an argon atmosphere, high-temperature resistant polytetrafluoroethylene propylene resin is extruded and coated onto the outermost layer of the cable to a thickness of 1.8 mm at an extrusion temperature of 320℃.

[0043] The plasma surface activation treatment in step one specifically involves placing a copper conductor in a vacuum chamber and evacuating it to a vacuum level of 1× Argon gas was introduced to maintain the pressure at 50 Pa, and the plasma was excited using a radio frequency power supply with a frequency of 13.56 MHz.

[0044] The modified ethylene-vinyl acetate copolymer was prepared by the following method: Ethylene-vinyl acetate copolymer (VA content 33wt%) was mixed with maleic anhydride graft at a mass ratio of 100:12 and reacted at 160℃ for 60 min, with nitrogen continuously purging during the reaction.

[0045] Functionalized ceramic microspheres are prepared through the following steps: I. Select hollow alumina microspheres with a particle size of 20 μm, and treat them under vacuum by introducing hexamethyldisilazane vapor at 30 sccm for 45 min; II. The microspheres treated in step I were immersed in an ethanol solution containing 1.0 wt% titanate and ultrasonically dispersed for 25 min; III. Functionalized ceramic microspheres with surface grafted siloxane-titanium ester composite layer were obtained by heat treatment at 300℃ for 2 hours under nitrogen protection.

[0046] The amount of functionalized ceramic microspheres added to the main insulating layer raw material is 32 wt%, and the microspheres contain: 85wt% alumina matrix 10wt% of surface-grafted siloxane layer Titanate catalyst layer 5wt%.

[0047] The conductive carbon black-graphene composite was prepared by the following method: Conductive carbon black with a particle size of 50 nm was mixed with graphene oxide at a mass ratio of 5:1 and added to an aqueous solution containing 0.1 mol / L ascorbic acid. The pH of the solution was controlled at ≤4. The reaction was carried out at 95 °C for 4 h. After freeze-drying, a three-dimensional interpenetrating network structure composite was obtained.

[0048] High-temperature resistant perfluoroethylene propylene resin contains the following components: Tetrafluoroethylene-hexafluoropropylene copolymer matrix: 100 parts; Nano titanium dioxide: 8 parts; Perfluorosulfonic acid resin powder: 5 parts; Perfluoropolyether lubricant: 1.2 parts.

[0049] Nano-titanium dioxide is pretreated with silane coupling agent KH-550. The pretreatment method is as follows: Nano-titanium dioxide was dispersed in an ethanol solution containing 3wt% KH-550, ultrasonicated for 30 min, and then dried at 110℃ for 2 h.

[0050] Step five, following irradiation crosslinking, also includes a heat stabilization treatment: The cable was placed in a 200℃ hot air circulation box for 6 hours, with a heating rate ≤5℃ / min.

[0051] Comparative Example 1: The difference between this comparative example and Example 1 is that no plasma surface activation treatment was performed when preparing the conductor in this comparative example.

[0052] Comparative Example 2 differs from Example 1 in that boron nanoparticles were not added when preparing the inner shielding layer in this comparative example.

[0053] Comparative Example 3 differs from Example 1 in that no functionalized ceramic microspheres were added during the preparation of the main insulating layer in this comparative example.

[0054] Comparative Example 4 differs from Example 1 in that nano-titanium dioxide was not added during the preparation of the sheath in this comparative example.

[0055] The high-temperature resistant power cables prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests. The test items and test methods are as follows: Dielectric strength testing was conducted in accordance with GB / T1408.1-2016 "Test Methods for Electrical Strength of Insulating Materials" Part 1: Tests at Power Frequency, measuring the voltage intensity at which the sample breaks down. The tensile strength retention rate test after heat aging was conducted according to GB / T 1040.3-2021 "Determination of tensile properties of plastics" Part 3: Test conditions for films and sheets, and the percentage of original strength retained was calculated. Flame retardancy testing was conducted in accordance with GB / T2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics" Part 2: Room Temperature Test, to determine the limiting oxygen index; Tensile strength testing was performed using a universal testing machine.

[0056] The test data of the high-temperature resistant power cables prepared in Examples 1-3 and Comparative Examples 1-4 are recorded in the table below:

[0057] By comparing and analyzing the data in the table, it can be seen that the high-temperature resistant power cables prepared using the processes in Examples 1-3 have significantly better performance than those prepared using the processes in Comparative Examples 1-4. This indicates that the invention, through its unique conductor interface activation treatment and composite shielding layer structure, eliminates the interfacial air gap between the conductor and the insulation layer under high-temperature conditions, avoiding the risk of partial discharge caused by electric field distortion. Simultaneously, it establishes a stable inner and outer double-layer electric field shielding mechanism, ensuring that the cable maintains a uniform electric field distribution under wide temperature range conditions. This fundamentally solves the technical defect of traditional cables caused by electric field instability due to thermal expansion. Furthermore, the invention utilizes a main insulation layer design with synergistic enhancement through functionalized ceramic microspheres and irradiation-thermal stabilization. The invention employs a synergistic crosslinking process to simultaneously enhance the high-temperature deformation resistance and molecular structure stability of insulation materials, overcoming the tendency of organic insulation materials to thermally degrade in high-temperature environments. This allows the cable to maintain stable dielectric properties and mechanical strength even under extreme temperature conditions, resolving the technical contradiction of the incompatibility between thermal stability and electrical performance in traditional insulation materials. Furthermore, the invention utilizes a three-dimensional interpenetrating outer shielding layer constructed from composite conductive materials and a nano-reinforced sheath system to achieve dynamic stability of the permeation network under high-temperature conditions. This prevents the shielding effectiveness from attenuating due to thermal motion of the conductive filler, while simultaneously providing the sheath with durable thermal protection, ensuring that the cable as a whole maintains the integrity of its mechanical barrier and the reliability of its electromagnetic shielding in high-temperature environments over the long term.

[0058] By comparing and analyzing the relevant data in the table, it can be seen that the high-temperature resistant power cable prepared by the molding process of this invention not only has good electrical insulation, thermal stability, and mechanical strength, but also demonstrates that the high-temperature resistant power cable provided by this invention has a broader market prospect and is more suitable for widespread application.

[0059] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0060] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-temperature resistant power cable, characterized in that: The cable consists of layers wrapped from the inside out: Plasma-activated copper conductors; Inner shielding layer containing boron nitride nanoparticles: volume resistivity ≤10³Ω·m; Ceramic microsphere-reinforced main insulation layer: dielectric strength ≥35kV / mm; Graphene composite outer shielding layer: surface resistance ≤10 4 Ω; High temperature resistant sheath: Long-term operating temperature ≥200℃.

2. The high-temperature resistant power cable according to claim 1, characterized in that: The manufacturing method of the high-temperature resistant power cable includes the following steps: Step 1: Conductor pretreatment. Annealed copper conductors are selected and plasma surface activation treatment is performed under inert gas protection. The activation power is 300-500W and the treatment time is 5-10 minutes. Step 2: Preparation of the inner shielding layer. Modified ethylene-vinyl acetate copolymer, nano boron nitride and silane coupling agent are mixed at a mass ratio of 100:15-20:0.5-1.5, melt-blended at 120-140℃ using a twin-screw extruder, and extruded to coat the surface of the pretreated conductor to form an inner shielding layer with a thickness of 0.3-0.5mm. Step 3: Construction of the main insulation layer. Cross-linked polyethylene, functionalized ceramic microspheres and antioxidants are placed in a mixer at a mass ratio of 100:25-35:1-3 and mixed at 150-170℃ for 20-30 minutes. The mixture is then coated onto the outside of the inner shielding layer through a three-layer co-extrusion device to form a main insulation layer with a thickness of 2.0-3.0 mm. Step 4: Forming the outer shielding layer. Conductive carbon black, graphene composite, vinyl elastomer and crosslinking agent are mixed in a mass ratio of 100:12-18:0.8-1.2 and coated onto the main insulating layer by extrusion coating, with a thickness of 0.4-0.6 mm. Step 5: Irradiation crosslinking. The cable is irradiated using an electron accelerator with an irradiation dose of 120-180 kGy and an energy of 2.5-3.5 MeV. Step Six: Sheath Extrusion. Under an argon atmosphere, high-temperature resistant polytetrafluoroethylene propylene resin is extruded and coated onto the outermost layer of the cable to a thickness of 1.2-1.8 mm at an extrusion temperature of 280-320℃.

3. The high-temperature resistant power cable according to claim 2, characterized in that: The plasma surface activation treatment in step one specifically involves placing a copper conductor in a vacuum chamber and evacuating it to a vacuum level of 5×. -1× Argon gas was introduced to maintain the pressure at 20-50 Pa, and the plasma was excited using a radio frequency power supply with a frequency of 13.56 MHz.

4. A high-temperature resistant power cable according to claim 2, characterized in that: The modified ethylene-vinyl acetate copolymer is prepared by the following method: Ethylene-vinyl acetate copolymer (VA content 28-33wt%) is mixed with maleic anhydride graft at a mass ratio of 100:8-12 and reacted at 140-160℃ for 40-60 min, with nitrogen continuously purging during the reaction.

5. A high-temperature resistant power cable according to claim 2, characterized in that: The functionalized ceramic microspheres are prepared through the following steps: Ⅰ. Select hollow alumina microspheres with a particle size of 10-20μm, and introduce hexamethyldisilazane vapor at 20-30sccm in a vacuum environment for 30-45min; II. Immerse the microspheres treated in step a in an ethanol solution containing 0.5-1.0 wt% titanate and ultrasonically disperse for 15-25 min; III. Under nitrogen protection, heat treatment at 200-300℃ for 1-2 hours yields functionalized ceramic microspheres with a surface grafted siloxane-titanium ester composite layer.

6. A high-temperature resistant power cable according to claim 2, characterized in that: The amount of functionalized ceramic microspheres added to the main insulating layer raw material is 28-32 wt%, and the microspheres contain: 80-85 wt% alumina matrix 8-12 wt% of surface-grafted siloxane layer Titanate catalyst layer 5-8 wt%.

7. A high-temperature resistant power cable according to claim 2, characterized in that: The conductive carbon black-graphene composite is prepared by the following method: Conductive carbon black with a particle size of 30-50 nm was mixed with graphene oxide at a mass ratio of 3:1-5:1 and added to an aqueous solution containing 0.1 mol / L ascorbic acid. The pH of the solution was controlled at ≤4. The mixture was reduced at 80-95℃ for 2-4 hours and then freeze-dried to obtain a three-dimensional interpenetrating network structure composite.

8. A high-temperature resistant power cable according to claim 2, characterized in that: The high-temperature resistant perfluoroethylene propylene resin comprises the following components: Tetrafluoroethylene-hexafluoropropylene copolymer matrix: 100 parts; Nano titanium dioxide: 5-8 parts; Perfluorosulfonic acid resin powder: 3-5 parts; Perfluoropolyether lubricant: 0.5-1.2 parts.

9. A high-temperature resistant power cable according to claim 8, characterized in that: The nano-titanium dioxide is pretreated with silane coupling agent KH-550. The pretreatment method is as follows: Nano-titanium dioxide was dispersed in an ethanol solution containing 2-3 wt% KH-550, ultrasonicated for 30 min, and then dried at 110℃ for 2 h.

10. A high-temperature resistant power cable according to claim 2, characterized in that: Step five, after irradiation crosslinking, also includes a heat stabilization treatment: Place the cable in a hot air circulation box at 180-200℃ for 4-6 hours, with a heating rate ≤5℃ / min.

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