High strength aluminum alloy medium voltage power cable

Abstract

The application relates to the technical field of cables, and discloses a high-strength aluminum alloy medium-voltage power cable. The high-strength aluminum alloy medium-voltage power cable comprises, from inside to outside, an aluminum alloy conductor and an insulation layer; the insulation layer is a cross-linked polyethylene nano-composite insulation material, and the raw material components of the cross-linked polyethylene nano-composite insulation material comprise, in terms of weight fractions, 100 parts of a base resin, 3-8 parts of core-shell-star compounded inorganic nano-filler, 0.5-1 part of an antioxidant and 1.5-2.5 parts of a cross-linking agent; the core-shell-star compounded inorganic nano-filler is silica-coated nano-aluminum nitride grafted with polyhedral oligomeric silsesquioxane, and is denoted as AlN@SiO2-POSS. In the application, the inorganic nano-composite filler is used to improve the thermal conductivity of the cable insulation layer, and meanwhile, the dielectric strength, mechanical tensile property and heat aging resistance of the cable are improved.

Description

Technical Field

[0001] This invention relates to the field of cable technology, specifically to a high-strength aluminum alloy medium-voltage power cable. Background Technology

[0002] With the acceleration of urbanization and industrialization, the application of medium-voltage power cables (6kV~35kV) is becoming increasingly widespread. To reduce costs and weight, aluminum alloy conductors are gradually replacing pure copper conductors. However, traditional unarmored lightweight aluminum alloy cables face the following technical bottlenecks: First, to improve the tensile strength and creep resistance of the aluminum alloy conductor, patent CN105719769B uses the method of adding the rare earth element scandium (Sc). However, scandium is extremely expensive, resulting in high cable manufacturing costs and hindering large-scale promotion. Second, medium-voltage cables generate a large amount of heat during operation, and traditional polyethylene insulation materials have poor thermal conductivity. Patent CN114286463B attempts to improve thermal conductivity by directly physical blending micron-sized inorganic fillers such as magnesium oxide and hexagonal boron nitride into the insulation layer. However, unmodified and unblended inorganic fillers are prone to agglomeration in the polymer matrix. This macroscopic agglomeration not only weakens the thermal conductivity but also causes severe distortion of the local electric field inside the insulation layer, becoming the source of "electrical trees," thus significantly reducing the cable's breakdown field strength and service life.

[0003] Furthermore, in actual cable extrusion production, conventional inorganic thermally conductive fillers have high surface energy and extremely poor compatibility with non-polar polyethylene matrix resins. During internal mixing and twin-screw high-temperature extrusion, the fillers are prone to secondary agglomeration or even phase separation, resulting in uneven insulation layer thickness and even clogging of the extruder filter, severely affecting the continuous production stability and insulation reliability of the finished cable. In addition, the simple addition of inorganic fillers often comes at the cost of sacrificing the mechanical elasticity and heat resistance elongation properties of cross-linked polyethylene, causing the cable to easily undergo thermomechanical deformation under high-temperature full-load operation. To solve the above technical problems, this invention proposes a new high-strength aluminum alloy medium-voltage power cable. Summary of the Invention

[0004] This invention proposes a high-strength aluminum alloy medium-voltage power cable, aiming to solve the technical problems of poor thermal conductivity of the insulation layer of traditional aluminum alloy cables, easy agglomeration of inorganic fillers leading to electric field distortion and decreased mechanical properties, and difficulties in extrusion processing in actual production.

[0005] The technical solution of the present invention is as follows: In a first aspect, the present invention proposes a high-strength aluminum alloy medium-voltage power cable, comprising, from the inside out: a high-strength heat-resistant aluminum alloy conductor and an insulation layer; the insulation layer is a cross-linked polyethylene nanocomposite insulation material, the raw material components of which, by weight, include: 100 parts of matrix resin, 3-8 parts of core-shell-star composite inorganic nanofiller, 0.5-1 parts of antioxidant, and 1.5-2.5 parts of cross-linking agent; wherein, the core-shell-star composite inorganic nanofiller is silica-coated nano-aluminum nitride grafted with polyhedral oligomeric silsesquioxane (POSS), denoted as AlN@SiO2-POSS.

[0006] As a further technical solution, the preparation method of the core-shell-star composite inorganic nanofiller includes: S1. Disperse nano-aluminum nitride (AlN) powder in an ethanol / water mixed solvent, add tetraethyl orthosilicate (TEOS) and ammonia, and grow a silica coating layer in situ on the surface of the nano-aluminum nitride using the sol-gel method. After washing and drying, AlN@SiO2 core-shell nanoparticles are obtained. S2. The AlN@SiO2 core-shell nanoparticles were reacted with silane coupling agent KH570 in toluene under reflux to obtain modified particles with carbon-carbon double bonds on the surface. S3. The modified particles and polyhedral oligomeric silsesquioxane (POSS) are added to the initiator and reacted under light irradiation. After washing, the core-shell-star composite inorganic nanofiller is obtained.

[0007] As a further technical solution, in S1, the average particle size of the nano-aluminum nitride is 30-80 nm, and the mass ratio of the nano-aluminum nitride, tetraethyl orthosilicate and ammonia is 100:(15-25):(5-15).

[0008] As a further technical solution, in S1, the reaction temperature of the sol-gel method is 20-30℃, and the reaction time is 4-8h.

[0009] As a further technical solution, in S2, the mass ratio of the AlN@SiO2 core-shell nanoparticles to the silane coupling agent is 100:(5-15).

[0010] As a further technical solution, in S2, the temperature of the reflux reaction is 70-90°C and the time is 8-16 hours.

[0011] As a further technical solution, in S3, the mass ratio of the modified particles to the polyhedral oligomeric silsesquioxane is 100:(15-25).

[0012] As a further technical solution, the initiator is the photoinitiator Irgacure 1173, and its dosage is 0.5% to 2% of the total mass of the modified particles and the polyhedral oligomeric silsesquioxane; the irradiation is ultraviolet light irradiation with a wavelength of 365 nm, and the reaction time is 3 to 6 hours.

[0013] As a further technical solution, the matrix resin is low-density polyethylene; the crosslinking agent is dicumyl peroxide; and the antioxidant is a compound of antioxidant 1010 and dithiodipropionate diester, wherein the mass ratio of antioxidant 1010 to dithiodipropionate diester is 1:(0.5-2).

[0014] Secondly, the present invention proposes a method for preparing a high-strength aluminum alloy medium-voltage power cable, which includes the following steps: The matrix resin, core-shell-star composite inorganic nanofiller, antioxidant and crosslinking agent are mixed evenly at 100~110℃, and then extruded and granulated by a twin-screw extruder; the insulation layer is simultaneously extruded on the outside of the alloy conductor and then enters the crosslinking tube for dry crosslinking to obtain a high-strength aluminum alloy medium-voltage power cable.

[0015] The working principle and beneficial effects of this invention are as follows: This invention improves the thermal, electrical, and mechanical properties of cable insulation layers by introducing AlN@SiO2-POSS core-shell-star composite inorganic nanofillers with finely regulated microstructures into the insulation layer. Specifically, this includes: First, aluminum nitride possesses excellent intrinsic thermal conductivity, but its surface is highly susceptible to hydrolysis and easily leads to electric field distortion. This invention addresses this by in-situ coating its surface with an amorphous silica insulating shell. While this introduces interfacial thermal resistance to some extent and sacrifices some of the intrinsic thermal conductivity of aluminum nitride, it not only protects the aluminum nitride from moisture corrosion but also utilizes the lower dielectric constant of SiO2 as a buffer layer to smooth the dielectric constant gradient between AlN and the matrix resin. This fundamentally weakens the local electric field distortion at the filler interface and significantly improves the dielectric strength.

[0016] Secondly, the outermost grafted thiol-modified POSS belongs to an inorganic-organic hybrid molecule (star structure) with a three-dimensional cage-like structure. POSS not only exhibits excellent thermodynamic compatibility with the polyethylene matrix, but its significant steric hindrance completely prevents secondary agglomeration between nanoparticles. This molecular-level uniform dispersion not only compensates for the thermal conductivity network blockage problem caused by the SiO2 coating layer, ensuring that the material maintains superior thermal conductivity compared to the pure matrix resin even at extremely low addition levels, but also completely eliminates mechanical stress concentration and partial discharge defects caused by filler agglomeration. This results in excellent flowability and dispersion uniformity of the insulating material during melt extrusion processing, avoiding practical production problems such as filter clogging and insulation eccentricity.

[0017] Third, the thiol groups on the periphery of the POSS molecule not only enhance the synergistic effect of antioxidation, but also, during the high-temperature dry crosslinking process of dicumyl peroxide (DCP), the residual double bonds and thiol groups on the filler surface can undergo coupling reactions with the crosslinked polyethylene macromolecular chains to form an inorganic particle-polymer crosslinking network. While the formation of this rigid three-dimensional crosslinking network, following the objective physical laws of polymers, leads to a reasonable decrease in the material's elongation at break, it significantly restricts the slippage of polymer molecular chains at high temperatures. This results in a substantial increase in the tensile strength of the cable insulation layer and a significant improvement in its resistance to thermal creep at high temperatures. All mechanical properties are far superior to the standard requirements for medium-voltage cables, ensuring the long-term operational safety of aluminum alloy cables under high-load heating conditions. Detailed Implementation

[0018] 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 some embodiments of the present invention, and not all 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.

[0019] It should be noted that the low-density polyethylene (LDPE) used in this invention is model 1I2A-1; Polyhedral oligomeric silsesquioxane (POSS), model number TH1550.

[0020] Example 1 A high-strength aluminum alloy medium-voltage power cable comprises, from the inside out: an aluminum alloy conductor and an insulation layer; the insulation layer is a cross-linked polyethylene nanocomposite insulation material, the raw material components of which, by weight, include: 100 parts of low-density polyethylene, 5.5 parts of core-shell-star composite inorganic nanofiller, 0.75 parts of antioxidant (antioxidant 1010 and dithiodipropionate diester in a mass ratio of 1:1.25), and 2.0 parts of dicumyl peroxide.

[0021] Among them, the core-shell-star composite inorganic nanofiller is silica-coated aluminum nitride nanoparticles grafted with polyhedral oligomeric silsesquioxane, denoted as AlN@SiO2-POSS.

[0022] The preparation methods of core-shell-star composite inorganic nanofillers include: S1. Take 100g of aluminum nitride nanoparticles with an average particle size of 50nm, disperse them in 500mL of ethanol / water mixed solvent (ethanol to water volume ratio of 4:1), add 20g of tetraethyl orthosilicate and 10g of ammonia water, and react at 25℃ for 6h by sol-gel method to grow a silica coating layer in situ on the surface of aluminum nitride nanoparticles. After centrifugation, washing and drying, AlN@SiO2 core-shell nanoparticles are obtained. S2. Take 100g of AlN@SiO2 core-shell nanoparticles and 10g of silane coupling agent KH570 and reflux them in 400mL of toluene at 80℃ for 12h. After the reaction is completed, centrifuge, wash and vacuum dry to obtain modified particles with carbon-carbon double bonds on the surface. S3. Take 100g of modified particles containing carbon-carbon double bonds and 20g of polyhedral oligomeric silsesquioxane, add 0.9g of photoinitiator Irgacure 1173 (accounting for 0.75% of the total mass of modified particles and POSS), irradiate under 365nm ultraviolet light for 4.5h to react, and after centrifugation, washing and vacuum drying, the core-shell-star composite inorganic nanofiller (AlN@SiO2-POSS) is obtained.

[0023] The manufacturing steps of high-strength aluminum alloy medium-voltage power cables include: Low-density polyethylene, core-shell-star composite inorganic nanofiller, antioxidant, and dicumyl peroxide are mixed evenly in an internal mixer at 105°C, and then extruded and granulated by a twin-screw extruder. Simultaneously, an insulation layer is extruded on the outside of the alloy conductor and then dry crosslinked in a crosslinking tube to obtain a high-strength aluminum alloy medium-voltage power cable.

[0024] Example 2 A high-strength aluminum alloy medium-voltage power cable comprises, from the inside out: an aluminum alloy conductor and an insulation layer; the insulation layer is a cross-linked polyethylene nanocomposite insulation material, the raw material components of which, by weight, include: 100 parts of low-density polyethylene, 3 parts of core-shell-star composite inorganic nanofiller, 0.5 parts of antioxidant (antioxidant 1010 and dithiodipropionate diester in a mass ratio of 1:0.5), and 1.5 parts of dicumyl peroxide.

[0025] Among them, the core-shell-star composite inorganic nanofiller is silica-coated aluminum nitride nanoparticles grafted with polyhedral oligomeric silsesquioxane, denoted as AlN@SiO2-POSS.

[0026] The preparation methods of core-shell-star composite inorganic nanofillers include: S1. Take 100g of aluminum nitride nanoparticles with an average particle size of 30nm, disperse them in 500mL of ethanol / water mixed solvent (ethanol to water volume ratio of 4:1), add 15g of tetraethyl orthosilicate and 5g of ammonia water, and react at 20℃ for 4h by sol-gel method to grow a silica coating layer in situ on the surface of aluminum nitride nanoparticles. After centrifugation, washing and drying, AlN@SiO2 core-shell nanoparticles are obtained. S2. Take 100g of AlN@SiO2 core-shell nanoparticles and 5g of silane coupling agent KH570 and reflux them in 400mL of toluene at 70℃ for 8h. After the reaction is completed, centrifuge, wash and vacuum dry to obtain modified particles with carbon-carbon double bonds on the surface. S3. Take 100g of modified particles containing carbon-carbon double bonds and 15g of polyhedral oligomeric silsesquioxane, add 0.575g of photoinitiator Irgacure 1173 (accounting for 0.5% of the total mass of modified particles and POSS), irradiate under 365nm ultraviolet light for 3h to react, and after centrifugation, washing and vacuum drying, the core-shell-star composite inorganic nanofiller (AlN@SiO2-POSS) is obtained.

[0027] The manufacturing steps of high-strength aluminum alloy medium-voltage power cables include: Low-density polyethylene, core-shell-star composite inorganic nanofiller, antioxidant, and dicumyl peroxide are mixed evenly in an internal mixer at 100°C, and then extruded and granulated by a twin-screw extruder. Simultaneously, an insulation layer is extruded on the outside of the alloy conductor and then dry crosslinked in a crosslinking tube to obtain a high-strength aluminum alloy medium-voltage power cable.

[0028] Example 3 A high-strength aluminum alloy medium-voltage power cable comprises, from the inside out: an aluminum alloy conductor and an insulation layer; the insulation layer is a cross-linked polyethylene nanocomposite insulation material, the raw material components of which, by weight, include: 100 parts of low-density polyethylene, 8 parts of core-shell-star composite inorganic nanofiller, 1 part of antioxidant (antioxidant 1010 and dithiodipropionate diester in a mass ratio of 1:2), and 2.5 parts of dicumyl peroxide.

[0029] Among them, the core-shell-star composite inorganic nanofiller is silica-coated aluminum nitride nanoparticles grafted with polyhedral oligomeric silsesquioxane, denoted as AlN@SiO2-POSS.

[0030] The preparation methods of core-shell-star composite inorganic nanofillers include: S1. Take 100g of aluminum nitride nanoparticles with an average particle size of 80nm, disperse them in 500mL of ethanol / water mixed solvent (ethanol to water volume ratio of 4:1), add 25g of tetraethyl orthosilicate and 15g of ammonia water, and react at 30℃ for 8h by sol-gel method to grow a silica coating layer in situ on the surface of aluminum nitride nanoparticles. After centrifugation, washing and drying, AlN@SiO2 core-shell nanoparticles are obtained. S2. Take 100g of AlN@SiO2 core-shell nanoparticles and 15g of silane coupling agent KH570 and reflux them in 400mL of toluene at 90℃ for 16h. After the reaction, centrifuge, wash and vacuum dry to obtain modified particles with carbon-carbon double bonds on the surface. S3. Take 100g of modified particles containing carbon-carbon double bonds and 25g of polyhedral oligomeric silsesquioxane, add 2.5g of photoinitiator Irgacure 1173 (accounting for 2% of the total mass of modified particles and POSS), irradiate under 365nm ultraviolet light for 6h to react, after centrifugation, washing and vacuum drying, the core-shell-star composite inorganic nanofiller (AlN@SiO2-POSS) is obtained.

[0031] The manufacturing steps of high-strength aluminum alloy medium-voltage power cables include: Low-density polyethylene, core-shell-star composite inorganic nanofiller, antioxidant, and dicumyl peroxide are mixed evenly in an internal mixer at 110°C, and then extruded and granulated by a twin-screw extruder. Simultaneously, an insulation layer is extruded on the outside of the alloy conductor and then dry crosslinked in a crosslinking tube to obtain a high-strength aluminum alloy medium-voltage power cable.

[0032] Comparative Example 1 Based on Example 1, adjustments were made, but unlike Example 1, unmodified nano-aluminum nitride (average particle size 50nm) was used to replace the core-shell-star composite inorganic nanofiller.

[0033] Comparative Example 2 Based on Example 1, adjustments were made. Unlike Example 1, a core-shell-star composite inorganic nanofiller that is only coated with SiO2 but not modified by POSS grafting was used to replace the core-shell-star composite inorganic nanofiller (the preparation method is the same as S1 in Example 1, and S2 and S3 are omitted).

[0034] Comparative Example 3 Based on Example 1, adjustments were made. Unlike Example 1, nano-aluminum nitride that was only surface-modified with KH570 but not coated with SiO2 (the preparation method is: omitting the SiO2 coating step of S1 and directly modifying nano-AlN with KH570 of S2) was used to replace the core-shell-star composite inorganic nanofiller.

[0035] Comparative Example 4 Based on Example 1, adjustments were made, but unlike Example 1, unmodified commercially available nano-silica was used to replace the core-shell-star composite inorganic nanofiller.

[0036] Comparative Example 5 Based on Example 1, adjustments were made, but unlike Example 1, unmodified commercially available nano boron nitride was used to replace the core-shell-star composite inorganic nanofiller.

[0037] Comparative Example 6 Based on Example 1, adjustments were made. Unlike Example 1, a physically blended mixture of nano-AlN and POSS (mass ratio 100:20, without any chemical bonding treatment) was used to replace the core-shell-star composite inorganic nanofiller by mass.

[0038] Comparative Example 7 Based on Example 1, adjustments were made. Unlike Example 1, a core-shell-star composite inorganic nanofiller was used. However, the amount of POSS in S3 was 5g, that is, the mass ratio of modified particles to POSS was 100:5, which is lower than the lower limit of the scope of the claims of 15 parts.

[0039] Comparative Example 8 Based on Example 1, adjustments were made. Unlike Example 1, a core-shell-star composite inorganic nanofiller was used. However, the amount of TEOS in S1 was 5g (i.e., the mass ratio of nano AlN to TEOS was 100:5, which is lower than the lower limit of the claim of 15 parts), resulting in an incomplete SiO2 coating layer.

[0040] Comparative Example 9 Based on Example 1, adjustments were made. Unlike Example 1, a core-shell-star composite inorganic nanofiller was used. However, the amount of silane coupling agent KH570 in S2 was 2g (i.e., the mass ratio of AlN@SiO2 to KH570 was 100:2, which is lower than the lower limit of the claim of 5 parts), resulting in insufficient carbon-carbon double bond grafting rate.

[0041] Comparative Example 10 The method is based on Example 1, but with adjustments. Unlike Example 1, no core-shell-star composite inorganic nanofiller is added, and the reduced amount is made up by low-density polyethylene.

[0042] Test Example 1: The high-strength aluminum alloy medium-voltage power cables prepared in the aforementioned examples and comparative examples were subjected to the following tests:

[0043] The test results are shown in Table 1 below: Table 1

[0044] Based on the foregoing data, it can be seen that the high-strength aluminum alloy medium-voltage power cable insulation layer proposed in this invention achieves a significant comprehensive balance in terms of electrical insulation, long-term heat resistance, and mechanical properties. Comparing Examples 1-3 with pure cross-linked polyethylene without any filler (Comparative Example 10), the addition of the specially formulated AlN@SiO2-POSS filler of this invention moderately increases the thermal conductivity of the material from 0.22 W / (m·K) to 0.30 W / (m·K). Simultaneously, the electrical insulation requirements are also met: its dielectric strength increases significantly from 16.5 kV / mm to a maximum of 34.1 kV / mm, and its volume resistivity increases by nearly an order of magnitude. In terms of mechanical properties, due to the formation of a robust chemical cross-linking network between the inorganic filler and the polymer matrix, the tensile strength is significantly increased from 14.5 MPa to 25.8 MPa, while the thermal elongation is greatly reduced (from 75% to 32%). At the same time, although the elongation at break is reduced to 230%~290% due to the restriction of polymer chain segment slippage by the cross-linking network, it still fully meets and exceeds the requirement of ≥200% for elongation at break of medium-voltage power cables, proving that this technical solution overcomes the fatal defect of material brittleness caused by traditional inorganic fillers.

[0045] Compared to directly adding unmodified pure nano-aluminum nitride (Comparative Example 1), although it achieved the highest thermal conductivity (0.32 W / (m·K)) in the group, the aggregation of nanoparticles led to changes in the local electric field strength of the insulation, reducing the breakdown strength to 15.5 kV / mm (even lower than the pure matrix), and stress concentration caused the material to fracture brittlely (the elongation at break dropped to 18.5%, making it completely unsuitable for cable production). Comparative Example 2 (SiO2 coating only) and Comparative Example 3 (KH570 grafting only) showed a slight improvement in performance, but due to the lack of steric hindrance and interfacial crosslinking effects of POSS, their overall electrical and mechanical properties could not reach the high standards of the examples. Comparative Example 6, which physically mixed POSS, demonstrated that simple blending alone could not form interfacial chemical bonds and could not anchor the matrix macromolecules and create a uniform electric field.

[0046] The test data from Comparative Examples 7-9 show that when the amount of POSS is too low (Comparative Example 7), the amount of TEOS is insufficient leading to an incomplete coating layer (Comparative Example 8), or the amount of silane coupling agent KH570 is too low resulting in a low double bond grafting rate (Comparative Example 9), the dielectric strength, mechanical strength, and aging performance of the materials all decrease significantly. This indicates that the proportions of the raw materials defined in this invention form a closely related synergistic system. Exceeding this specific proportion range will prevent the achievement of a balance between thermal conductivity, insulation, and mechanical toughness, fully demonstrating the rationality and irreplaceability of the parameter protection range of this invention.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-strength aluminum alloy medium-voltage power cable, characterized in that, From the inside out, it includes: an aluminum alloy conductor and an insulating layer; the insulating layer is a cross-linked polyethylene nanocomposite insulating material, whose raw material components, by weight, include: 100 parts of matrix resin, 3-8 parts of core-shell-star composite inorganic nanofiller, 0.5-1 parts of antioxidant, and 1.5-2.5 parts of cross-linking agent; wherein, the core-shell-star composite inorganic nanofiller is silica-coated nano-aluminum nitride grafted with polyhedral oligomeric silsesquioxane, denoted as AlN@SiO2-POSS.

2. The high-strength aluminum alloy medium-voltage power cable according to claim 1, characterized in that, The preparation method of the core-shell-star composite inorganic nanofiller includes: S1. Disperse nano-aluminum nitride powder in an ethanol / water mixed solvent, add tetraethyl orthosilicate and ammonia, and grow a silica coating layer in situ on the surface of nano-aluminum nitride by sol-gel method. After washing and drying, AlN@SiO2 core-shell nanoparticles are obtained. S2. The AlN@SiO2 core-shell nanoparticles were reacted with a silane coupling agent under reflux in toluene to obtain modified particles; S3. The modified particles and polyhedral oligomeric silsesquioxane are added to the initiator and reacted under light irradiation. After washing, the core-shell-star composite inorganic nanofiller is obtained.

3. The high-strength aluminum alloy medium-voltage power cable according to claim 2, characterized in that, In S1, the average particle size of the nano-aluminum nitride is 30-80 nm, and the mass ratio of the nano-aluminum nitride, tetraethyl orthosilicate and ammonia is 100:(15-25):(5-15).

4. A high-strength aluminum alloy medium-voltage power cable according to claim 2, characterized in that, In S1, the sol-gel reaction temperature is 20–30°C and the reaction time is 4–8 h.

5. A high-strength aluminum alloy medium-voltage power cable according to claim 2, characterized in that, In S2, the mass ratio of the AlN@SiO2 core-shell nanoparticles to the silane coupling agent is 100:(5-15).

6. A high-strength aluminum alloy medium-voltage power cable according to claim 2, characterized in that, In S2, the reflux reaction is carried out at a temperature of 70–90°C for 8–16 hours.

7. A high-strength aluminum alloy medium-voltage power cable according to claim 2, characterized in that, In S3, the mass ratio of the modified particles to the polyhedral oligomeric silsesquioxane is 100:(15-25).

8. A high-strength aluminum alloy medium-voltage power cable according to claim 2, characterized in that, The initiator is the photoinitiator Irgacure 1173, and its dosage is 0.5% to 2% of the total mass of the modified particles and the polyhedral oligomeric silsesquioxane; the irradiation is ultraviolet light irradiation with a wavelength of 365 nm and a reaction time of 3 to 6 hours.

9. A high-strength aluminum alloy medium-voltage power cable according to claim 1, characterized in that, The matrix resin is low-density polyethylene; the crosslinking agent is dicumyl peroxide; the antioxidant is a compound of antioxidant 1010 and dithiodipropionate diester, wherein the mass ratio of antioxidant 1010 to dithiodipropionate diester is 1:(0.5-2).

10. A method for preparing a high-strength aluminum alloy medium-voltage power cable, used to prepare the high-strength aluminum alloy medium-voltage power cable as described in any one of claims 1-9, characterized in that, Includes the following steps: The matrix resin, core-shell-star composite inorganic nanofiller, antioxidant and crosslinking agent are mixed evenly at 100~110℃ and extruded into granules; an insulation layer is simultaneously extruded on the outside of the aluminum alloy conductor and then dry crosslinked in a crosslinking tube to obtain a high-strength aluminum alloy medium-voltage power cable.

Images