Aluminum-clad steel-cored aluminum stranded wire for coastal high-corrosion environment and preparation method thereof

Abstract

The present application relates to the field of wire and cable manufacturing, and particularly relates to an aluminum-clad steel core aluminum stranded wire for coastal high-corrosion environment and a preparation method thereof, comprising a steel core layer, the steel core layer is an alloy-coated steel wire with a zinc-aluminum-magnesium alloy coating on the surface, the outer surface of the alloy-coated steel wire is coated with an aluminum coating layer, and the aluminum coating layer and the alloy-coated steel wire jointly form an aluminum-clad steel core; the present application builds a multi-stage synergistic corrosion-resistant structure in the internal interface, outer layer matrix and overall gap of the wire through interface diffusion treatment of the alloy coating layer and the aluminum coating layer, component optimization and surface passivation of the outer layer corrosion-resistant aluminum alloy, and gradient filling and surface curing of different functional sealing materials between wire layers. Compared with the prior art, the present application effectively inhibits galvanic corrosion and crevice penetration in a salt spray and humid environment, prolongs the service life of the wire in a strong corrosion environment, and the preparation process is connected to the existing production line, the operation is controllable, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of wire and cable manufacturing, and in particular to an aluminum-clad steel-core aluminum stranded wire for use in highly corrosive coastal environments and its preparation method. Background Technology

[0002] Overhead transmission lines in coastal areas are exposed to harsh atmospheric environments with high salt spray and high humidity for extended periods. The steel core coating, aluminum cladding, and interlayer interfaces of aluminum-clad steel core stranded wire are highly susceptible to chloride ion corrosion, resulting in galvanic corrosion and crevice corrosion. This further reduces the conductor's conductive cross-section and mechanical strength, seriously threatening the safe operation of the transmission lines. Conventional galvanized steel wire stranded wire and ordinary anti-corrosion grease are no longer sufficient to meet the practical engineering requirements for long-term corrosion resistance of conductors in coastal environments.

[0003] In existing technologies, aluminum-clad steel cores typically use pure zinc-plated steel wire to cover the aluminum layer. In humid coastal environments, the zinc plating is consumed rapidly, and there is a lack of an effective diffusion barrier layer at the steel-aluminum interface. This leads to damage points on the outer aluminum layer, forming a strong galvanic corrosion circuit with a large cathode and a small anode, accelerating the corrosion and fracture of the steel core. Conventional anti-corrosion grease filled between the stranded layers of the conductor is prone to flow, oxidation, and erosion by rainwater during long-term outdoor operation, making it difficult to continuously seal the gaps inside the conductor. If the surface of the outer aluminum alloy wire is treated with chromium passivation, it faces environmental regulations. Without surface treatment, pitting corrosion is highly likely. These protective measures, whether singular or simply combined, are insufficient to synergistically suppress the corrosion process from multiple dimensions, including interface barrier, substrate corrosion resistance, and gap sealing. Consequently, the actual service life of the conductor in coastal environments is far shorter than the design expectation.

[0004] Therefore, based on the relevant technologies mentioned above, there is an urgent need to develop an aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments and its preparation method. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide an aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments and its preparation method, so as to solve the problems of severe interface corrosion, gap sealing failure, easy loss of protective layer and insufficient corrosion resistance in the prior art.

[0006] To achieve the above objectives, the present invention provides an aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments and a method for preparing the same.

[0007] An aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments, comprising, from the inside out: The steel core layer is an alloy-coated steel wire with a zinc-aluminum-magnesium alloy coating on its surface. The alloy-coated steel wire is covered with an aluminum cladding layer, and the aluminum cladding layer and the alloy-coated steel wire together form an aluminum-clad steel core. The aluminum-clad steel core is stranded with an aluminum alloy wire layer, which is composed of aluminum alloy wire, and the surface of the aluminum alloy wire is treated with a passivation liquid to form a passivation film. The gap between the aluminum-clad steel core and the aluminum alloy wire is filled with corrosion-inhibiting sealant, and the outermost layer is coated with anti-corrosion grease.

[0008] Preferably, the preparation steps of the alloy-coated steel wire are as follows: Step A1: Under a nitrogen atmosphere, zinc, aluminum and magnesium are added to a graphite crucible, heated to 480-500℃, and stirred for 10-20 minutes at a speed of 80-120 rpm until the metal melts. After stirring is complete, let stand for 5-15 minutes to remove slag, and then cool to 450-460℃ to obtain an alloy solution. Step A2: Straighten the carbon steel wire and put it into the alkaline degreasing liquid spraying zone. The linear speed is 15-25m / min, the spraying pressure is 0.3-0.5MPa, the liquid temperature is 60-70℃, and the cleaning time is 15-25s. Wash it twice with deionized water at a water temperature of 40-50℃ for 10-12s each time. Then place it in a reduction annealing furnace, introduce a mixed gas of nitrogen and hydrogen, raise the temperature to 680-720℃, and hold for 60-80s. After annealing, cool it down to 500-550℃ to obtain the treated steel wire. Step A3: Under a nitrogen atmosphere, immerse the treated steel wire in the alloy solution, heat to 450-460℃, linear speed 18-22m / min, immersion coating for 3.6-5.4s, after immersion coating is completed, purge with nitrogen at a pressure of 0.1-0.15MPa, cool with air to 100-150℃, and obtain alloy-coated steel wire.

[0009] By hot-dip galvanizing the steel wire surface with a ternary alloy coating of zinc, aluminum, and magnesium instead of the traditional pure zinc coating, the addition of aluminum can form a dense alumina protective film on the coating surface, while the trace addition of magnesium can refine the coating grain structure and promote the formation of a stable composite corrosion product layer in the early stage of corrosion. This alloy coating has a more positive corrosion potential and a lower corrosion rate than the pure zinc coating in a chloride ion environment, and can block the penetration of coastal salt spray into the steel substrate for a long time, thus delaying the corrosion failure of the aluminum-clad steel core coating from the source.

[0010] Preferably, the mass ratio of zinc, aluminum and magnesium in step A1 is 94.5-95:5-5.5:0.1-0.3; The volume ratio of nitrogen to hydrogen in step A2 is 19:1.

[0011] Preferably, the preparation steps of the alkaline degreasing solution in step A2 are as follows: Add sodium carbonate and sodium tripolyphosphate to deionized water, heat to 40-50℃, stir for 15-25 minutes at 80-100 rpm, add sodium hydroxide, reduce the stirring speed to 60-80 rpm, stir for 15-25 minutes, then reduce the stirring speed to 50-60 rpm, add sodium dodecylbenzene sulfonate, stir for 10-12 minutes, add sodium fatty alcohol polyoxyethylene ether sulfate, continue stirring for 10-20 minutes, after stirring is complete, add deionized water, adjust the pH to 12-12.5 to obtain an alkaline degreasing solution; The mass ratio of sodium carbonate, sodium tripolyphosphate, sodium hydroxide, sodium dodecylbenzenesulfonate, and sodium fatty alcohol polyoxyethylene ether sulfate is 3.1-3.2:1:1.6-1.7:0.36-0.4:1.86-1.9.

[0012] Preferably, the preparation steps of the corrosion-inhibiting sealant are as follows: Add organic bentonite to polyalphaolefin base oil, heat to 90-100℃, stir for 45-55 minutes at 800-1000 rpm. After stirring, reduce the speed to 200-300 rpm and the temperature to 68-72℃. Add flake aluminum powder and stir for 35-45 minutes. Add benzotriazole and mercaptobenzothiazole and stir for 5-7 minutes. Add microcrystalline wax and antioxidant 1010 and stir for 3-5 minutes. After adding, continue stirring for 25-35 minutes. Place in a three-roll mill with the front roller temperature at 25-30℃, the middle roller temperature at 40-45℃, and the rear roller temperature at 50-55℃. Grind 3-5 times. After grinding, let stand for 20-30 minutes to degas, and obtain corrosion-inhibiting sealant. The antioxidant 1010 is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; The mass ratio of the organic bentonite, polyalphaolefin base oil, aluminum powder, benzotriazole, mercaptobenzothiazole, microcrystalline wax and antioxidant 1010 is 1:6.7-6.8:2.1-2.2:0.25-0.27:0.08-0.1:0.18-0.22:0.07-0.08.

[0013] Preferably, the preparation steps of the preservative are as follows: Under yellow safety light illumination, add organic bentonite to polyalphaolefin base oil, heat to 90-100℃, stir for 45-55 minutes at 800-1000 rpm, and after stirring, reduce the speed to 150-250 rpm and the temperature to 55-65℃. Add aliphatic polyurethane diacrylate and stir for 20-30 minutes. Add the reactive diluent tripropylene glycol diacrylate and stir for 10-15 minutes. Add the photoinitiator 1-hydroxycyclohexylphenyl ketone and stir for 15-20 minutes. Then add flake aluminum powder and stir for 35-45 minutes. Add benzotriazole and mercaptobenzothiazole and stir for 5-7 minutes. After the addition is complete, continue stirring for 25-35 minutes. After stirring is complete, let stand for degassing for 25-35 minutes to obtain the preservative grease. The corrosion-inhibiting sealant is applied in a liquid state during a differential temperature injection process, fully impregnating and filling the gaps inside the conductor. After cooling, it solidifies to form a flexible filler that can accommodate the thermal expansion and contraction and vibration deformation of the conductor. At the same time, the anti-corrosion grease is filled in the outermost gap. After being irradiated with ultraviolet light, its surface can solidify within seconds to form a tough sealing film, which can resist rainwater erosion and wind and sand abrasion. In addition, since the inner un-illuminated parts remain flexible paste, they form a layered seal between the gap and the outer layer. When the outer solid film is damaged, the inner grease can flow to fill and self-heal, achieving long-life, maintenance-free interlayer corrosion protection.

[0014] The mass ratio of the organic bentonite, polyalphaolefin base oil, aliphatic polyurethane diacrylate, reactive diluent, photoinitiator, aluminum powder, benzotriazole and mercaptobenzothiazole is 1:6.2-6.3:1.85-1.90:0.48-0.52:0.185-0.19:3-3.2:0.27-0.29:0.092-0.094.

[0015] Preferably, the passivation solution is prepared using the following steps: Add cerium nitrate crystals to deionized water, heat to 25-35℃, stir for 10-20 min, add hexafluorotitanic acid, stir for 10-20 min, add sodium fluoride, stir for 10-20 min, after stirring is complete, add 5% wt nitric acid solution, adjust pH to 3.5-4.5, let stand to defoam for 10-15 min, and obtain passivation solution; The mass ratio of the cerium nitrate crystals, deionized water, hexafluorotitanic acid and sodium fluoride is 0.03-0.05:1:0.014-0.016:0.0034-0.0036.

[0016] Preferably, the preparation steps of the aluminum-clad steel core are as follows: Step B1: Under a nitrogen atmosphere, add aluminum ingots to a melting furnace, heat to 730-750℃, add 10% aluminum-cerium alloy, stir for 8-12 minutes at a speed of 100-120 rpm, refine for 15-25 minutes, after refining is complete, let stand for 10-20 minutes to remove slag, place on a semi-continuous casting machine, cast at a temperature of 700-720℃, with a diameter of 9.5-12 mm, to obtain an alloy rod billet; Step B2: Under a nitrogen atmosphere, place the alloy-coated steel wire on a continuous extrusion press at a linear speed of 5-15 m / min, heat to 350-400℃, hold for 40-60 s, feed the alloy billet into the feed roller of the continuous extrusion press, heat to 450-500℃, extrusion pressure 1.5-3.0 GPa, after coating is completed, place it in an annealing furnace, heat the first zone to 370-390℃ and hold for 8-9 h, heat the second zone to 270-290℃ and hold for 4-5 h, after holding is completed, cool down to obtain aluminum-clad steel core; The mass ratio of the aluminum ingot to the aluminum-cerium alloy is 1:0.018-0.022.

[0017] After the aluminum layer is extruded and coated onto the surface of the alloy-coated steel wire, a gradient diffusion annealing treatment is immediately performed in different temperature zones. At the same time, the first high-temperature holding stage allows the interfacial atoms between the zinc-aluminum-magnesium coating and the outer aluminum cladding to fully interdiffuse, generating a continuous aluminum-zinc-iron intermetallic compound diffusion barrier layer in situ. This transforms the mechanical pressing of the steel substrate, alloy coating, and aluminum cladding into a complete metallurgical bond, completely eliminating interlayer gaps and blocking the channels for corrosive media to penetrate along the interface via capillary action. In addition, the second medium-temperature holding stage effectively eliminates diffusion stress, prevents the generation of microcracks at the interface, and ensures the long-term reliable stability of the interface bond.

[0018] Preferably, the aluminum alloy wire is prepared using the following steps: Step C1: Under a nitrogen atmosphere, add aluminum ingots to a melting furnace, heat to 730-750℃, add 10% aluminum-silicon alloy and 10% aluminum-cerium alloy, stir for 10-20 minutes at a speed of 80-100 rpm, add magnesium ingots, reduce the speed to 60-80 rpm, stir for 4-6 minutes, refine for 12-15 minutes, let stand for 20-30 minutes to remove slag, cool to 700-720℃, place in a continuous casting machine with a diameter of 9.5-12 mm, cool down to obtain aluminum rod billets; Step C2: Load the aluminum rod billet into a heat treatment furnace, heat it to 560-570℃, hold it for 100-140 min, after holding, water quench it, transfer it to an aging furnace, heat it to 170-180℃, hold it for 6-7 h, and then place it in a continuous wire drawing machine with a cemented carbide texture drawing die, with a groove depth of 15-25 μm, a drawing speed of 8-12 m / s, lubricant cooling, and a diameter of 2.0-4.5 mm to obtain aluminum alloy wire; By adding trace amounts of magnesium, silicon, and cerium to aluminum, the resistance of aluminum alloy wire to pitting and intergranular corrosion is significantly improved while ensuring high conductivity. At the same time, cerium can purify the grain boundaries of the aluminum matrix, reduce impurity segregation, and introduce rare earth oxides into the surface oxide film to enhance its density. Furthermore, by performing chromium-free rare earth conversion film passivation treatment on the aluminum wire, a cerium oxide-titanium oxide composite passivation film is formed on the surface, sealing micropores and processing defects. In addition, because the film layer is extremely thin and has no effect on its conductivity, and its synergistic effect with the microalloyed matrix, the aluminum wire can have excellent salt spray resistance even without any grease coating, providing the conductor with full-cycle corrosion protection from the inside out.

[0019] The mass ratio of the aluminum ingot, aluminum-silicon alloy, aluminum-cerium alloy and magnesium ingot is 1:0.042-0.043:0.014-0.016:0.008-0.009.

[0020] A method for preparing aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments, the specific steps of which are as follows: Step S1: Immerse the aluminum alloy wire in the passivation solution, heat it to 20-30℃, immerse for 1-3 minutes, drain for 10-20 seconds, rinse with deionized water, and dry in an oven to obtain the passivated aluminum alloy wire. Step S2: Place the aluminum-clad steel core in a frame-type stranding machine with a pitch ratio of 14-18, a stranding speed of 100-200 rpm, induction heating at a frequency of 10-20 kHz and a travel speed of 10-20 m / min, raising the temperature to 70-80℃. Add passivated aluminum alloy wire with a pitch ratio of 12-16, and add corrosion-inhibiting sealant at a temperature of 85-95℃ and an injection pressure of 0.1-0.3 MPa. After the conductor exits the stranding die, cool it to 20-30℃, then add anti-corrosion grease at a temperature of 55-65℃ and an injection pressure of 0.3-0.5 MPa. After injection, place the machine in an annular ultraviolet irradiation channel with a wavelength of 360-370 nm and an irradiation intensity of 200-400 mW / cm². 2 Irradiation time is 4-8 seconds. After irradiation, the temperature is reduced to 20-30℃ to obtain aluminum-clad steel core aluminum stranded wire.

[0021] The beneficial effects of this invention are: This invention provides an aluminum-clad steel-core aluminum stranded wire for use in highly corrosive coastal environments and its preparation method. The invention utilizes interfacial diffusion treatment between the steel core alloy coating and the aluminum cladding, composition optimization and surface passivation of the outer corrosion-resistant aluminum alloy, and gradient filling and surface curing of different functional sealing materials between the conductor layers. This constructs a multi-level synergistic corrosion-resistant structure within the conductor's internal interface, outer matrix, and overall gaps. Compared to existing technologies, this invention effectively inhibits galvanic corrosion and crevice penetration in salt spray and humid environments, extends the service life of the conductor in highly corrosive environments, and its preparation process is compatible with existing production lines, offering controllable operation and broad application prospects. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a bar chart showing the retention rate of residual tensile strength in this invention; Figure 2 This is a bar chart showing the contact resistance before and after the spray test in this invention; Figure 3 This is a line graph showing the rate of change of contact resistance in this invention; Figure 4 This is a bar chart of the azimuth fill rate test results of this invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0025] Example 1: Preparation of an alkaline degreasing solution: Add 310g of sodium carbonate and 100g of sodium tripolyphosphate to 1500mL of deionized water, heat to 40℃, stir for 25min at 80rpm, add 160g of sodium hydroxide, reduce the stirring speed to 80rpm, stir for 15min, then reduce the stirring speed to 60rpm, add 36g of sodium dodecylbenzenesulfonate, stir for 10min, add 186g of sodium fatty alcohol polyoxyethylene ether sulfate, continue stirring for 20min, after stirring is complete, add deionized water, adjust the pH to 12-12.5 to obtain an alkaline degreasing solution.

[0026] Example 2: Preparation of an alkaline degreasing solution: Add 315g of sodium carbonate and 100g of sodium tripolyphosphate to 1500mL of deionized water, heat to 45℃, stir for 20min at 90rpm, add 165g of sodium hydroxide, reduce the stirring speed to 70rpm, stir for 20min, then reduce the stirring speed to 55rpm, add 38g of sodium dodecylbenzenesulfonate, stir for 11min, add 188g of sodium fatty alcohol polyoxyethylene ether sulfate, continue stirring for 15min, after stirring is complete, add deionized water, adjust the pH to 12-12.5 to obtain an alkaline degreasing solution.

[0027] Example 3: Preparation of an alkaline degreasing solution: Add 320g of sodium carbonate and 100g of sodium tripolyphosphate to 1500mL of deionized water, heat to 50℃, stir for 15min at 100rpm, add 170g of sodium hydroxide, reduce the stirring speed to 60rpm, stir for 25min, then reduce the stirring speed to 50rpm, add 40g of sodium dodecylbenzenesulfonate, stir for 12min, add 190g of sodium fatty alcohol polyoxyethylene ether sulfate, continue stirring for 10min, after stirring is complete, add deionized water, adjust the pH to 12-12.5 to obtain an alkaline degreasing solution.

[0028] Example 4: Preparation of an alloy-coated steel wire: S1: Under a nitrogen atmosphere, add 945g of zinc, 50g of aluminum and 1g of magnesium to a graphite crucible, heat to 480℃, wait for the metal to melt, stir for 20min at 80rpm, after stirring is complete, let stand for 15min, remove scum, cool to 450℃ to obtain alloy solution. S2: The carbon steel wire is straightened and placed into the alkaline degreasing liquid (Example 1) spray zone at a linear speed of 15 m / min, a spray pressure of 0.5 MPa, a liquid temperature of 60°C, and is cleaned for 25 seconds. It is then washed twice with deionized water at a water temperature of 40°C for 12 seconds each time. It is then placed in a reduction annealing furnace, and a mixture of nitrogen and hydrogen is introduced. The temperature is raised to 680°C and held for 80 seconds to complete the annealing. The temperature is then lowered to 500°C to obtain the treated steel wire. S3: Under a nitrogen atmosphere, the treated steel wire is immersed in the alloy solution, heated to 450℃, linear speed 22m / min, and immersed for 3.6s. After immersion, nitrogen is purged at a pressure of 0.15MPa, and the wire is cooled to 100℃ to obtain an alloy-coated steel wire.

[0029] Example 5: Preparation of an alloy-coated steel wire: S1: Under a nitrogen atmosphere, add 948g of zinc, 53g of aluminum and 2g of magnesium to a graphite crucible, heat to 490℃, wait for the metal to melt, stir for 15min at 100rpm, after stirring is complete, let stand for 10min, remove slag, cool to 455℃ to obtain alloy solution. S2: The carbon steel wire is straightened and placed into the alkaline degreasing liquid (Example 2) spray zone at a linear speed of 20 m / min, a spray pressure of 0.4 MPa, a liquid temperature of 65°C, and cleaned for 20 seconds. It is then washed twice with deionized water at a water temperature of 45°C for 11 seconds each time. It is then placed in a reduction annealing furnace, and a mixture of nitrogen and hydrogen is introduced. The temperature is raised to 700°C and held for 70 seconds to complete the annealing. The temperature is then lowered to 530°C to obtain the treated steel wire. S3: Under a nitrogen atmosphere, the treated steel wire is immersed in the alloy solution, heated to 455℃, linear speed 20m / min, and immersed for 4.5s. After immersion, nitrogen is purged at a pressure of 0.13MPa, and the wire is cooled to 130℃ to obtain an alloy-coated steel wire.

[0030] Example 6: Preparation of an alloy-coated steel wire: S1: Under a nitrogen atmosphere, add 950g of zinc, 55g of aluminum and 3g of magnesium to a graphite crucible, heat to 500℃, wait for the metal to melt, stir for 10min at 120rpm, after stirring is complete, let stand for 5min, remove slag, cool to 460℃ to obtain alloy solution. S2: The carbon steel wire is straightened and placed into the alkaline degreasing liquid (Example 3) spray zone at a linear speed of 15m / min, a spray pressure of 0.5MPa, a liquid temperature of 60℃, and is cleaned for 25s. It is then washed twice with deionized water at a water temperature of 40℃ for 12s each time. It is then placed in a reduction annealing furnace, and a mixture of nitrogen and hydrogen is introduced. The temperature is raised to 680℃ and held for 80s. After annealing, the temperature is lowered to 500℃ to obtain the treated steel wire. S3: Under a nitrogen atmosphere, the treated steel wire is immersed in the alloy solution, heated to 460℃, linear speed 18m / min, and immersed for 5.4s. After immersion, nitrogen is purged at a pressure of 0.1MPa, and the wire is cooled to 150℃ to obtain an alloy-coated steel wire.

[0031] Example 7: Preparation of an aluminum-clad steel core: S1: Under a nitrogen atmosphere, 1000g of aluminum ingot is added to a melting furnace, heated to 730℃, 18g of 10% aluminum-cerium alloy is added, stirred for 8 minutes at 120 rpm, and refined for 15 minutes. After refining, the ingot is allowed to stand for 20 minutes to remove slag. The ingot is then placed on a semi-continuous casting machine and cast at 700℃ with a diameter of 9.5-12mm to obtain an alloy rod billet. S2: Under a nitrogen atmosphere, the alloy-coated steel wire (Example 4) is placed on a continuous extrusion press at a linear speed of 5 m / min, heated to 400°C, held for 40 s, and the alloy billet is fed into the feed roller of the continuous extrusion press. The temperature is raised to 500°C and the extrusion pressure is 1.5 GPa. After coating is completed, it is placed in an annealing furnace. The first zone is heated to 390°C and held for 8 h, and the second zone is heated to 290°C and held for 4 h. After holding is completed, it is cooled to obtain an aluminum-clad steel core.

[0032] Example 8: Preparation of an aluminum-clad steel core: S1: Under a nitrogen atmosphere, 1000g of aluminum ingot is added to a melting furnace, heated to 740℃, 20g of 10% aluminum-cerium alloy is added, stirred for 10min at 110rpm, and refined for 20min. After refining, it is allowed to stand for 15min to remove slag, and then placed on a semi-continuous casting machine. The casting temperature is 710℃, and the diameter is 9.5-12mm to obtain an alloy rod billet. S2: Under a nitrogen atmosphere, the alloy-coated steel wire (Example 5) is placed on a continuous extrusion press at a linear speed of 10 m / min, heated to 370°C, held for 50 s, and the alloy billet is fed into the feed roller of the continuous extrusion press. The temperature is raised to 470°C and the extrusion pressure is 2.3 GPa. After coating is completed, it is placed in an annealing furnace. The first zone is heated to 380°C and held for 8.5 h, and the second zone is heated to 280°C and held for 4.5 h. After holding is completed, it is cooled to obtain an aluminum-clad steel core.

[0033] Example 9: Preparation of an aluminum-clad steel core: S1: Under a nitrogen atmosphere, 1000g of aluminum ingot is added to a melting furnace, heated to 750℃, 22g of 10% aluminum-cerium alloy is added, stirred for 8 minutes at 120 rpm, and refined for 15 minutes. After refining, the ingot is allowed to stand for 20 minutes to remove slag. The ingot is then placed on a semi-continuous casting machine and cast at 700℃ with a diameter of 9.5-12mm to obtain an alloy rod billet. S2: Under a nitrogen atmosphere, the alloy-coated steel wire (Example 6) is placed on a continuous extrusion press at a linear speed of 15 m / min, heated to 350°C, held for 60 s, and the alloy billet is fed into the feed roller of the continuous extrusion press. The temperature is raised to 450°C and the extrusion pressure is 3.0 GPa. After coating is completed, it is placed in an annealing furnace. The first zone is heated to 370°C and held for 9 h, and the second zone is heated to 270°C and held for 5 h. After holding is completed, it is cooled to obtain an aluminum-clad steel core.

[0034] Example 10: Preparation of a corrosion-inhibiting sealant: Add 100g of organic bentonite to 670g of polyalphaolefin base oil, heat to 90℃, stir for 55min at 800rpm. After stirring, reduce the speed to 300rpm and the temperature to 68℃. Add 210g of flake aluminum powder and stir for 45min. Add 25g of benzotriazole and 8g of mercaptobenzothiazole and stir for 5min. Add 18g of microcrystalline wax and 7g of antioxidant 1010 and stir for 5min. After adding, continue stirring for 25min. Place in a three-roll mill with the front roller temperature at 30℃, the middle roller temperature at 40℃, and the rear roller temperature at 55℃. Grind 3 times. After grinding, let stand for degassing for 30min to obtain corrosion-inhibiting sealant.

[0035] Example 11: Preparation of a corrosion-inhibiting sealant: Add 100g of organic bentonite to 675g of polyalphaolefin base oil, heat to 95℃, stir for 50min at 900rpm, after stirring is complete, reduce the speed to 250rpm and the temperature to 70℃, add 215g of flake aluminum powder, stir for 40min, add 26g of benzotriazole and 9g of mercaptobenzothiazole, stir for 6min, add 20g of microcrystalline wax and 7.5g of antioxidant 1010, stir for 4min, after addition is complete, continue stirring for 30min, place in a three-roll mill, front roller temperature 27℃, middle roller temperature 43℃, rear roller temperature 53℃, grind 4 times, after grinding is complete, let stand for degassing for 25min to obtain corrosion-inhibiting sealant.

[0036] Example 12: Preparation of a corrosion-inhibiting sealant: Add 100g of organic bentonite to 680g of polyalphaolefin base oil, heat to 100℃, stir for 45min at 1000rpm, after stirring is complete, reduce the speed to 200rpm and the temperature to 72℃, add 220g of flake aluminum powder, stir for 35min, add 27g of benzotriazole and 10g of mercaptobenzothiazole, stir for 7min, add 22g of microcrystalline wax and 8g of antioxidant 1010, stir for 3min, after addition is complete, continue stirring for 35min, place in a three-roll mill, front roller temperature 25℃, middle roller temperature 45℃, rear roller temperature 50℃, grind 5 times, after grinding is complete, let stand for degassing for 20min to obtain corrosion-inhibiting sealant.

[0037] Example 13: Preparation of a preservative: Under yellow safety light illumination, 100g of organic bentonite was added to 620g of polyalphaolefin base oil. The mixture was heated to 90℃ and stirred for 55 minutes at 800 rpm. After stirring, the stirring speed was reduced to 250 rpm and the temperature was lowered to 55℃. 185g of aliphatic polyurethane diacrylate was added and stirred for 30 minutes. 48g of reactive diluent tripropylene glycol diacrylate was added and stirred for 10 minutes. 18.5g of photoinitiator 1-hydroxycyclohexylphenyl ketone was added and stirred for 20 minutes. 300g of flake aluminum powder was added and stirred for 35 minutes. 27g of benzotriazole and 9.2g of mercaptobenzothiazole were added and stirred for 7 minutes. After addition, stirring was continued for 25 minutes. After stirring was complete, the mixture was allowed to stand for degassing for 35 minutes to obtain the preservative grease.

[0038] Example 14: Preparation of a preservative: Under yellow safety light illumination, 100g of organic bentonite was added to 625g of polyalphaolefin base oil. The mixture was heated to 95℃ and stirred for 50 minutes at 900 rpm. After stirring, the stirring speed was reduced to 200 rpm and the temperature was lowered to 60℃. 188g of aliphatic polyurethane diacrylate was added and stirred for 25 minutes. 50g of reactive diluent tripropylene glycol diacrylate was added and stirred for 13 minutes. 18.8g of photoinitiator 1-hydroxycyclohexylphenyl ketone was added and stirred for 18 minutes. 310g of flake aluminum powder was added and stirred for 40 minutes. 28g of benzotriazole and 9.3g of mercaptobenzothiazole were added and stirred for 6 minutes. After the addition was complete, stirring was continued for 30 minutes. After stirring was complete, the mixture was allowed to stand for degassing for 30 minutes to obtain the preservative grease.

[0039] Example 15: Preparation of a preservative: Under yellow safety light illumination, 100g of organic bentonite was added to 630g of polyalphaolefin base oil. The mixture was heated to 100℃ and stirred for 45 minutes at 1000 rpm. After stirring, the stirring speed was reduced to 150 rpm and the temperature was lowered to 65℃. 190g of aliphatic polyurethane diacrylate was added and stirred for 20 minutes. 52g of reactive diluent tripropylene glycol diacrylate was added and stirred for 15 minutes. 19g of photoinitiator 1-hydroxycyclohexylphenyl ketone was added and stirred for 15 minutes. 320g of flake aluminum powder was added and stirred for 45 minutes. 29g of benzotriazole and 9.4g of mercaptobenzothiazole were added and stirred for 5 minutes. After the addition was complete, stirring was continued for 35 minutes. After stirring was complete, the mixture was allowed to stand for degassing for 25 minutes to obtain the preservative grease.

[0040] Example 16: Preparation of a passivation solution: Add 3g of cerium nitrate crystals to 100g of deionized water, heat to 25℃, stir for 20min, add 1.4g of hexafluorotitanic acid, stir for 10min, add 0.34g of sodium fluoride, stir for 20min, after stirring is complete, add 5%wt nitric acid solution, adjust pH to 3.5-4.5, let stand for 10min to defoam, and obtain passivation solution.

[0041] Example 17: Preparation of a passivation solution: Add 4g of cerium nitrate crystals to 100g of deionized water, heat to 30℃, stir for 15min, add 1.5g of hexafluorotitanic acid, stir for 15min, add 0.35g of sodium fluoride, stir for 15min, after stirring is complete, add 5%wt nitric acid solution, adjust pH to 3.5-4.5, let stand for 13min to defoam, and obtain passivation solution.

[0042] Example 18: Preparation of a passivation solution: Add 5g of cerium nitrate crystals to 100g of deionized water, heat to 35℃, stir for 10min, add 1.6g of hexafluorotitanic acid, stir for 20min, add 0.36g of sodium fluoride, stir for 10min, after stirring is complete, add 5%wt nitric acid solution, adjust pH to 3.5-4.5, let stand for 15min to defoam, and obtain passivation solution.

[0043] Example 19: Preparation of an aluminum alloy wire: S1: Under a nitrogen atmosphere, add 100g of aluminum ingot to a melting furnace, heat to 730℃, add 4.2g of 10% aluminum-silicon alloy and 1.4g of 10% aluminum-cerium alloy, stir for 20min at 80rpm, add 0.8g of magnesium ingot, reduce the speed to 80rpm, stir for 4min, refine for 15min, let stand for 20min, remove slag, cool to 720℃, place in a continuous casting machine with a diameter of 9.5-12mm, cool down to obtain aluminum rod billet; S2: The aluminum rod blank is placed in a heat treatment furnace, heated to 560℃, held for 140 min, and after holding, it is water-quenched and transferred to an aging furnace, heated to 170℃, held for 7 h, and then placed in a continuous wire drawing machine with a carbide texture drawing die. The groove depth is 15 μm, the drawing speed is 12 m / s, and the wire is cooled with lubricant. The diameter is 2.0-4.5 mm to obtain aluminum alloy wire.

[0044] Example 20: Preparation of an aluminum alloy wire: S1: Under a nitrogen atmosphere, add 100g of aluminum ingot to a melting furnace, heat to 740℃, add 4.25g of 10% aluminum-silicon alloy and 1.5g of 10% aluminum-cerium alloy, stir for 15min at 90rpm, add 0.85g of magnesium ingot, reduce the speed to 70rpm, stir for 5min, refine for 13.5min, let stand for 25min, remove slag, cool to 710℃, place in a continuous casting machine with a diameter of 9.5-12mm, cool down to obtain aluminum rod billet; S2: The aluminum rod blank is placed in a heat treatment furnace, heated to 565℃, held for 120 minutes, and then water-quenched after holding. It is then transferred to an aging furnace, heated to 175℃, held for 6.5 hours, and then placed in a continuous wire drawing machine with a carbide texture drawing die. The groove depth is 20μm, the drawing speed is 10m / s, and the wire is cooled with lubricant. The diameter is 2.0-4.5mm, and the aluminum alloy wire is obtained.

[0045] Example 21: Preparation of an aluminum alloy wire: S1: Under a nitrogen atmosphere, add 100g of aluminum ingot to a melting furnace, heat to 750℃, add 4.3g of 10% aluminum-silicon alloy and 1.6g of 10% aluminum-cerium alloy, stir for 10min at 100rpm, add 0.9g of magnesium ingot, reduce the speed to 60rpm, stir for 6min, refine for 12min, let stand for 30min, remove slag, cool to 700℃, place in a continuous casting machine with a diameter of 9.5-12mm, cool down to obtain aluminum rod billet; S2: The aluminum rod blank is placed in a heat treatment furnace, heated to 570℃, held for 100 minutes, and then water-quenched after holding. It is then transferred to an aging furnace, heated to 180℃, held for 6 hours, and then placed in a continuous wire drawing machine with a carbide texture drawing die. The groove depth is 25μm, the drawing speed is 8m / s, and the wire is cooled with lubricant. The diameter is 2.0-4.5mm, and the aluminum alloy wire is obtained.

[0046] Example 22: A method for preparing aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments: S1: Immerse the aluminum alloy wire (Example 19) in the passivation solution (Example 16), heat it to 20°C, immerse it for 3 minutes, after immersion, drain the solution for 10 seconds, rinse with deionized water, and dry it in an oven to obtain the passivated aluminum alloy wire. S2: Place the aluminum-clad steel core (Example 7) in a frame-type stranding machine with a pitch ratio of 18, a stranding speed of 100 rpm, induction heating at a frequency of 20 kHz, a travel speed of 10 m / min, and heat to 80°C. Add passivated aluminum alloy wire with a pitch ratio of 12, and add corrosion-inhibiting sealant (Example 10) at a temperature of 95°C and an injection pressure of 0.1 MPa. After the conductor exits the stranding die, cool to 30°C, and then add anti-corrosion grease (Example 13) at a temperature of 55°C and an injection pressure of 0.5 MPa. After injection, place the conductor in an annular ultraviolet irradiation channel with a wavelength of 360 nm and an irradiation intensity of 400 mW / cm². 2 Irradiation time is 8 seconds. After irradiation is completed, the temperature is reduced to 20℃ to obtain aluminum-clad steel core aluminum stranded wire.

[0047] Example 23: A method for preparing aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments: S1: Immerse the aluminum alloy wire (Example 20) in the passivation solution (Example 17), heat it to 25°C, immerse it for 2 minutes, after immersion, drain the solution for 15 seconds, rinse with deionized water, and dry it in an oven to obtain the passivated aluminum alloy wire. S2: Place the aluminum-clad steel core (Example 8) in a frame-type stranding machine with a pitch ratio of 16, a stranding speed of 150 rpm, induction heating at a frequency of 15 kHz and a travel speed of 15 m / min, and heat to 75°C. Add passivated aluminum alloy wire with a pitch ratio of 14, and add corrosion-inhibiting sealant (Example 11) at a temperature of 90°C and an injection pressure of 0.2 MPa. After the conductor exits the stranding die, cool to 25°C, and then add anti-corrosion grease (Example 14) at a temperature of 60°C and an injection pressure of 0.4 MPa. After injection, place the conductor in an annular ultraviolet irradiation channel with a wavelength of 365 nm and an irradiation intensity of 300 mW / cm². 2 Irradiation time is 6 seconds. After irradiation is completed, the temperature is reduced to 25℃ to obtain aluminum-clad steel core aluminum stranded wire.

[0048] Example 24: A method for preparing aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments: S1: Immerse the aluminum alloy wire (Example 21) in the passivation solution (Example 18), heat it to 30°C, immerse it for 1 minute, after immersion, drain the solution for 20 seconds, rinse with deionized water, and dry it in an oven to obtain the passivated aluminum alloy wire. S2: Place the aluminum-clad steel core (Example 9) in a frame-type stranding machine with a pitch ratio of 18, a stranding speed of 100 rpm, induction heating at a frequency of 20 kHz and a travel speed of 10 m / min, and heat to 80°C. Add passivated aluminum alloy wire with a pitch ratio of 12, and add corrosion-inhibiting sealant (Example 12) at a temperature of 95°C and an injection pressure of 0.1 MPa. After the conductor exits the stranding die, cool to 30°C, and then add anti-corrosion grease (Example 15) at a temperature of 55°C and an injection pressure of 0.5 MPa. After injection, place the conductor in an annular ultraviolet irradiation channel with a wavelength of 360 nm and an irradiation intensity of 400 mW / cm². 2 Irradiation time is 4 seconds. After irradiation is completed, the temperature is cooled to 30℃ to obtain aluminum-clad steel core aluminum stranded wire.

[0049] Example 25: A method for preparing aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments: S1: The aluminum alloy wire (Example 19) is placed in a circulating spray passivation device. The passivation solution (Example 16) is sprayed evenly onto the surface of the aluminum alloy wire from the upper and lower fan-shaped nozzles at a spray pressure of 0.23 MPa by a stainless steel centrifugal pump. The temperature of the passivation solution is 20°C and the spraying time is 1-3 min. The passivation solution in the storage tank is filtered through a 50 μm filter bag and then recycled. The circulation flow rate is 30 L / min. After spraying, the solution is drained for 10-20 s, rinsed with deionized water, and dried in an oven to obtain the passivated aluminum alloy wire. S2: Place the aluminum-clad steel core (Example 7) in a frame-type stranding machine with a pitch ratio of 18, a stranding speed of 100 rpm, induction heating at a frequency of 20 kHz, a travel speed of 10 m / min, and heat to 80°C. Add passivated aluminum alloy wire with a pitch ratio of 12, and add corrosion-inhibiting sealant (Example 10) at a temperature of 95°C and an injection pressure of 0.1 MPa. After the conductor exits the stranding die, cool to 30°C, and then add anti-corrosion grease (Example 13) at a temperature of 55°C and an injection pressure of 0.5 MPa. After injection, place the conductor in an annular ultraviolet irradiation channel with a wavelength of 360 nm and an irradiation intensity of 400 mW / cm². 2 Irradiation time is 8 seconds. After irradiation is completed, the temperature is reduced to 20℃ to obtain aluminum-clad steel core aluminum stranded wire.

[0050] Comparative Example 1: Compared with Example 24, this comparative example omits the gradient diffusion annealing process in the aluminum-clad steel core preparation process. That is, after the aluminum rod blank is continuously extruded and coated on the surface of the alloy-coated steel wire, it is directly air-cooled to room temperature and wound up without undergoing the first zone high-temperature diffusion annealing and the second zone medium-temperature stress-relief annealing treatment. The remaining steps and parameters are the same, and this comparative example will not repeat them. Finally, aluminum-clad steel core aluminum stranded wire is obtained.

[0051] Comparative Example 2: Compared with Example 24, this comparative example only replaces "alloy coated steel wire" with "hot-dip galvanized steel wire". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, aluminum-clad steel core aluminum stranded wire is obtained.

[0052] Comparative Example 3: Compared with Example 24, this comparative example only replaces "corrosion-inhibiting sealant and anti-corrosion grease" with "lithium-based anti-corrosion lubricant for ordinary steel wire rope". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, aluminum-clad steel core aluminum stranded wire is obtained.

[0053] Comparative Example 4: Compared with Example 24, this comparative example does not add aluminum-cerium master alloy and magnesium ingots in the preparation process of aluminum alloy wire. All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, aluminum-clad steel core aluminum stranded wire is obtained.

[0054] Performance testing: According to the GB / T 10125-2021 testing standard, the YWX / Q-250 salt spray corrosion test chamber was used; Take aluminum-clad steel core aluminum stranded wires from Examples 22-25 and Comparative Examples 1-4 respectively, cut 300mm, and make 3 samples of each. Clean with anhydrous ethanol, blow dry, and immerse 50mm of each end of the sample in epoxy resin and cure at room temperature for 24h. The sample was placed in a salt spray test chamber, with a blank zinc plate as a control. The concentration of sodium chloride solution in the salt water chamber was 50 g / L ± 5 g / L, the temperature of the saturated tank was 47℃ ± 2℃, the temperature of the test chamber was 35℃ ± 2℃, the spray pressure was 70-170 kPa, and the salt spray deposition rate was 1.0-2.0 mL / (80 cm²). 2 )·h, cumulative spraying for 3000h. Every 500h, take out, clean with deionized water, air dry, visually inspect and record the corrosion morphology. After the inspection and recording are completed, before resuspending the sample, confirm that the temperature inside the chamber has recovered to 35℃±2℃ and stabilized for more than 15 minutes, and continue the subsequent spraying test.

[0055] Residual breaking force test (reference) Figure 1 ) According to the GB / T 4909.3-2009 testing standard, the WEW-600 universal testing machine was used. After completing the 3000h spray test, the sample was taken out, washed with deionized water, air-dried, the epoxy resin sealing end was sawn off, and it was placed in the testing machine. The tensile speed was 20mm / min, the clamp spacing was 200mm, the testing machine was started and the sample was loaded at a uniform speed until it broke. The breaking force value was recorded and recorded as F1. Take 200mm of aluminum-clad steel core aluminum stranded wire from Examples 22-25 and Comparative Examples 1-4 respectively, and conduct experiments according to the above method to measure the tensile force value F0. Formula for calculating the remaining tensile strength retention rate:

[0056] Table 1 Test Results of Examples and Comparative Examples

[0057] Line-to-line contact resistance test (reference) Figure 2-3 ) The QJ57 DC resistance tester was used in accordance with the GB / T 30551-2014 test standard. After completing the 3000-hour spray test, the sample was taken out, washed with deionized water, and air-dried. The probe of the DC resistance tester was used to contact the surface of the outermost two adjacent aluminum alloy wires of the conductor. The probe spacing was 10 mm. Five measurement points were selected evenly, and the arithmetic mean of the resistance values ​​of the five points was taken as the inter-line contact resistance value of the sample. The initial inter-line contact resistance of the same batch of finished conductors that had not undergone the salt spray test was measured using the same method. Formula for calculating the rate of change of contact resistance:

[0058] Table 2. Test results of contact resistance between lines in the examples and comparative examples.

[0059] Orientation fill rate and sealant integrity assessment (reference) Figure 4 ) Samples from Examples 22-25 and Comparative Examples 1-4 that have completed salt spray testing, residual tensile force testing and contact resistance testing were selected, and one section was randomly selected and placed under a 500 lx light source for inspection. The integrity of its sealing film was recorded. Evaluation criteria: Cracking: Observe the surface of the sealing film for linear or network cracks. Record the number, approximate length, and distribution of cracks. If a single crack is longer than 5 mm or penetrates more than 1 / 4 of the circumference of the conductor, it is assessed as "obvious cracking".

[0060] Peeling: Observe whether there is separation, lifting, or large-scale peeling between the sealing film and the aluminum strand substrate. Record the percentage of the peeled area to the total exposed area.

[0061] Bubbling: Observe whether there are bubbly bulges on the surface of the sealing film.

[0062] Starting from one end of the exposed section of the sample along the axial direction of the conductor, cut into the gap between the outermost aluminum strand and the second outermost layer. The cutting edge should maintain a 15-20° angle with the conductor axis. The cutting depth should not exceed the radius of the outermost single aluminum strand. Advance the cutting edge along the circumference of the conductor until the outermost single aluminum strand is completely separated from the inner strands. Hold one end of the separated strand with pointed tweezers and peel it off from the stranded structure in the opposite direction of the original twisting direction of the conductor. During the peeling process, the clamping force of the tweezers should only act on the aluminum strand itself and should not touch the sealing material in the gap. After peeling off one strand, observe and record the presence of the sealing material in the gap below that strand.

[0063] After the outermost aluminum strands are completely stripped, use a clean, soft brush to gently sweep along the conductor axis over the exposed secondary outer layer surface to remove any small amount of aluminum shavings that may be generated during the stripping process, without touching the gap filling material. Confirm that the start and end points of the exposed section of the conductor along the axial direction are clearly marked. Use a steel ruler with a graduation of 0.5 mm to measure at 0°, 90°, 180°, and 270° along the conductor axis. The definition of a continuous filling section is: the sealing material is continuously distributed along the axial direction without any visible gaps or breaks. A single continuous filling section with a length greater than 5 mm is considered a valid filling section. If there are two or more filling sections on the same axis, the cumulative length of each valid filling section is taken as the filling length in that direction. Calculation of azimuth fill rate:

[0064] Table 3 Test Results of Examples and Comparative Examples

[0065] Note: The sampling length is 200mm of the exposed section.

[0066] Data Analysis: As can be seen from Tables 1-3, the aluminum-clad steel core aluminum stranded wire prepared by this invention has better salt spray corrosion resistance and long-term sealing stability, as well as more stable conductive contact performance after 3000 hours of neutral salt spray test. In contrast, Comparative Example 1, due to the absence of a temperature-zone gradient diffusion annealing process during the preparation of the aluminum-clad steel core, failed to form a continuous aluminum-zinc-iron intermetallic compound diffusion barrier layer between the zinc-aluminum-magnesium alloy coating on the steel core surface and the outer aluminum cladding layer. Macroscopic physical gaps remained at the interface, and after a 3000-hour salt spray test, the coating exhibited localized blistering, rust spots seeped between the strands, and the remaining tensile strength retention rate decreased to 82.4%, while the contact resistance change rate increased to 8.6%. This was because the steel substrate, alloy coating, and aluminum cladding were only mechanically pressed together, failing to achieve metallurgical bonding. Furthermore, the macroscopic physical gaps between the layers provided capillary penetration channels for corrosive media. The lack of a diffusion barrier layer meant that once the outer aluminum layer showed signs of damage, chloride ions could directly penetrate the steel-aluminum interface and cause galvanic corrosion. In addition, the absence of a second-zone medium-temperature stress-relief annealing treatment meant that residual stress at the interface could lead to microcracks, further accelerating corrosion propagation. In Comparative Example 2, replacing the zinc-aluminum-magnesium alloy coated steel wire with hot-dip galvanized pure zinc steel wire significantly accelerated the corrosion rate of the steel core coating in the chloride ion environment. After 3000 hours of salt spray testing, the steel core coating was severely corroded, resulting in multiple areas of red rust, bulging of the aluminum cladding, a remaining tensile strength retention rate of only 73.5%, and a contact resistance change rate as high as 12.7%. Therefore, its corrosion resistance was far lower than that of Example 24. This is because the pure zinc coating is consumed quickly in the chloride ion environment, and the lack of aluminum prevents the formation of a dense alumina protective film on the coating surface. In addition, the lack of magnesium prevents the refinement of the coating grain structure, thus promoting the formation of a stable composite corrosion product layer. This further leads to a significant reduction in the electrochemical protection life of the coating on the steel substrate. Furthermore, the large potential difference between the corrosion potential of the pure zinc coating and the outer aluminum cladding makes it easier to form an galvanic corrosion pair in the humid coastal environment, accelerating the consumption of the coating. In Comparative Example 3, replacing the corrosion-inhibiting sealant and anti-corrosion grease with ordinary lithium-based anti-corrosion lubricating grease for steel wire ropes resulted in a significant loss of the anti-corrosion grease adhering to the conductor under long-term salt spray and thermal cycling conditions. This caused the gap filling rate to plummet from over 92% to 41%. White spots and pits appeared on the surface of the aluminum wire due to the loss of effective sealing protection. The reason for this is that ordinary lithium-based anti-corrosion lubricating grease lacks a thixotropic thickening system and photocuring cross-linking ability. Furthermore, during long-term outdoor operation, the anti-corrosion lubricating grease is prone to flow, oxidation, and rainwater erosion, thus failing to form a continuous seal for the gaps inside the conductor. At the same time, this lubricating grease does not have the liquid wetting and in-situ solidification characteristics of differential temperature injection, making it difficult to fully penetrate and fill the micron-level gaps between the conductor strands. In addition, the lack of an ultraviolet light-curing sealing film as an outer locking barrier causes the overall gap sealing layer of the conductor to completely lose its self-repairing ability, allowing corrosive media to easily penetrate into the interior of the conductor. Comparative Example 4, due to the absence of aluminum-cerium master alloy and magnesium ingots in the aluminum alloy wire preparation process, and the retention of silicon elements introduced by the aluminum-silicon master alloy, resulted in a significant deficiency in the intrinsic pitting and intergranular corrosion resistance of the outer aluminum wire. After 3000 hours of salt spray testing, the surface of the aluminum wire was covered with pitting pits, and intergranular corrosion cracks appeared in some areas. The remaining tensile strength retention rate dropped to 88.6%, and the contact resistance change rate was 5.4%. The reason for this is that the lack of trace magnesium elements prevented the formation of a dispersed Mg2Si strengthening phase, which reduced the strength and hardness of the aluminum wire. Due to the lack of rare earth cerium elements, the aluminum matrix grain boundaries could not be purified and impurity segregation could not be reduced. The surface natural oxide film lacked the reinforcement of rare earth oxides and was not dense enough. Chloride ions were more likely to induce pitting corrosion at surface micropores and processing defects and extend into the matrix. Example 25 uses a cyclic spray passivation process to passivate aluminum alloy wires. The remaining processes are the same as in Example 22. After a 3000-hour salt spray test, the surface sealing film is intact, the residual tensile strength retention rate is 96.1%, the gap filling rate is 93%, and the contact resistance change rate is 2.3%. All performance characteristics are basically equivalent to those of Example 22, which uses immersion passivation. This shows that the chromium-free rare earth passivation treatment of the present invention can be implemented by either immersion or cyclic spraying, both of which are feasible passivation process paths. Therefore, both methods can form a cerium oxide-titanium oxide composite passivation film on the surface of the aluminum wire, effectively sealing micropores and processing defects. Moreover, the film layer is extremely thin and does not affect the inter-wire contact resistance. Together with the microalloyed substrate, it gives the aluminum wire excellent salt spray resistance, providing a flexible process choice for actual production.

[0067] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0068] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments, characterized in that, From the inside out, it includes: The steel core layer is an alloy-coated steel wire with a zinc-aluminum-magnesium alloy coating on its surface. The alloy-coated steel wire is covered with an aluminum cladding layer, and the aluminum cladding layer and the alloy-coated steel wire together form an aluminum-clad steel core. The aluminum-clad steel core is stranded with an aluminum alloy wire layer, which is composed of aluminum alloy wire, and the surface of the aluminum alloy wire is treated with a passivation liquid to form a passivation film. The gap between the aluminum-clad steel core and the aluminum alloy wire is filled with corrosion-inhibiting sealant, and the outermost layer is coated with anti-corrosion grease.

2. The aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments according to claim 1, characterized in that, The preparation steps of the alloy-coated steel wire are as follows: Step A1: Under a nitrogen atmosphere, zinc, aluminum and magnesium are added to a graphite crucible, heated to 480-500℃, and stirred for 10-20 minutes at a speed of 80-120 rpm until the metal melts. After stirring is complete, let stand for 5-15 minutes to remove slag, and then cool to 450-460℃ to obtain an alloy solution. Step A2: Straighten the carbon steel wire and put it into the alkaline degreasing liquid spraying zone. The linear speed is 15-25m / min, the spraying pressure is 0.3-0.5MPa, the liquid temperature is 60-70℃, and the cleaning time is 15-25s. Wash it twice with deionized water at a water temperature of 40-50℃ for 10-12s each time. Then place it in a reduction annealing furnace, introduce a mixed gas of nitrogen and hydrogen, raise the temperature to 680-720℃, and hold for 60-80s. After annealing, cool it down to 500-550℃ to obtain the treated steel wire. Step A3: Under a nitrogen atmosphere, immerse the treated steel wire in the alloy solution, heat to 450-460℃, linear speed 18-22m / min, immersion coating for 3.6-5.4s, after immersion coating is completed, purge with nitrogen at a pressure of 0.1-0.15MPa, cool with air to 100-150℃, and obtain alloy-coated steel wire.

3. The aluminum-clad steel-core aluminum stranded wire for use in highly corrosive coastal environments according to claim 2, characterized in that, The mass ratio of zinc, aluminum and magnesium mentioned in step A1 is 94.5-95:5-5.5:0.1-0.3; The volume ratio of nitrogen to hydrogen in step A2 is 19:

1.

4. The aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments according to claim 2, characterized in that, The preparation steps of the alkaline degreasing solution in step A2 are as follows: Add sodium carbonate and sodium tripolyphosphate to deionized water, heat to 40-50℃, stir for 15-25 minutes at 80-100 rpm, add sodium hydroxide, reduce the stirring speed to 60-80 rpm, stir for 15-25 minutes, then reduce the stirring speed to 50-60 rpm, add sodium dodecylbenzene sulfonate, stir for 10-12 minutes, add sodium fatty alcohol polyoxyethylene ether sulfate, continue stirring for 10-20 minutes, after stirring is complete, add deionized water, adjust the pH to 12-12.5 to obtain an alkaline degreasing solution; The mass ratio of sodium carbonate, sodium tripolyphosphate, sodium hydroxide, sodium dodecylbenzenesulfonate, and sodium fatty alcohol polyoxyethylene ether sulfate is 3.1-3.2:1:1.6-1.7:0.36-0.4:1.86-1.

9.

5. The aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments according to claim 1, characterized in that, The preparation steps of the corrosion-inhibiting sealant are as follows: Add organic bentonite to polyalphaolefin base oil, heat to 90-100℃, stir for 45-55 minutes at 800-1000 rpm. After stirring, reduce the speed to 200-300 rpm and the temperature to 68-72℃. Add flake aluminum powder and stir for 35-45 minutes. Add benzotriazole and mercaptobenzothiazole and stir for 5-7 minutes. Add microcrystalline wax and antioxidant 1010 and stir for 3-5 minutes. After adding, continue stirring for 25-35 minutes. Place in a three-roll mill with the front roller temperature at 25-30℃, the middle roller temperature at 40-45℃, and the rear roller temperature at 50-55℃. Grind 3-5 times. After grinding, let stand for 20-30 minutes to degas, and obtain corrosion-inhibiting sealant. The mass ratio of the organic bentonite, polyalphaolefin base oil, aluminum powder, benzotriazole, mercaptobenzothiazole, microcrystalline wax and antioxidant 1010 is 1:6.7-6.8:2.1-2.2:0.25-0.27:0.08-0.1:0.18-0.22:0.07-0.

08.

6. The aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments according to claim 1, characterized in that, The preparation steps of the preservative are as follows: Under yellow safety light illumination, add organic bentonite to polyalphaolefin base oil, heat to 90-100℃, stir for 45-55 minutes at 800-1000 rpm, and after stirring, reduce the speed to 150-250 rpm and the temperature to 55-65℃. Add aliphatic polyurethane diacrylate and stir for 20-30 minutes. Add the reactive diluent tripropylene glycol diacrylate and stir for 10-15 minutes. Add the photoinitiator 1-hydroxycyclohexylphenyl ketone and stir for 15-20 minutes. Then add flake aluminum powder and stir for 35-45 minutes. Add benzotriazole and mercaptobenzothiazole and stir for 5-7 minutes. After the addition is complete, continue stirring for 25-35 minutes. After stirring is complete, let stand for degassing for 25-35 minutes to obtain the preservative grease. The mass ratio of the organic bentonite, polyalphaolefin base oil, aliphatic polyurethane diacrylate, reactive diluent, photoinitiator, aluminum powder, benzotriazole and mercaptobenzothiazole is 1:6.2-6.3:1.85-1.90:0.48-0.52:0.185-0.19:3-3.2:0.27-0.29:0.092-0.

094.

7. The aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments according to claim 1, characterized in that, The passivation solution is prepared in the following steps: Add cerium nitrate crystals to deionized water, heat to 25-35℃, stir for 10-20 min, add hexafluorotitanic acid, stir for 10-20 min, add sodium fluoride, stir for 10-20 min, after stirring is complete, add 5% wt nitric acid solution, adjust pH to 3.5-4.5, let stand to defoam for 10-15 min, and obtain passivation solution; The mass ratio of the cerium nitrate crystals, deionized water, hexafluorotitanic acid and sodium fluoride is 0.03-0.05:1:0.014-0.016:0.0034-0.0036.

8. The aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments according to claim 1, characterized in that, The preparation steps of the aluminum-clad steel core are as follows: Step B1: Under a nitrogen atmosphere, add aluminum ingots to a melting furnace, heat to 730-750℃, add 10% aluminum-cerium alloy, stir for 8-12 minutes at a speed of 100-120 rpm, refine for 15-25 minutes, after refining is complete, let stand for 10-20 minutes to remove slag, place on a semi-continuous casting machine, cast at a temperature of 700-720℃, with a diameter of 9.5-12 mm, to obtain an alloy rod billet; Step B2: Under a nitrogen atmosphere, place the alloy-coated steel wire on a continuous extrusion press at a linear speed of 5-15 m / min, heat to 350-400℃, hold for 40-60 s, feed the alloy billet into the feed roller of the continuous extrusion press, heat to 450-500℃, extrusion pressure 1.5-3.0 GPa, after coating is completed, place it in an annealing furnace, heat the first zone to 370-390℃ and hold for 8-9 h, heat the second zone to 270-290℃ and hold for 4-5 h, after holding is completed, cool down to obtain aluminum-clad steel core; The mass ratio of the aluminum ingot to the aluminum-cerium alloy is 1:0.018-0.

022.

9. The aluminum-clad steel-core aluminum stranded wire for use in highly corrosive coastal environments according to claim 1, characterized in that, The preparation steps of the aluminum alloy wire are as follows: Step C1: Under a nitrogen atmosphere, add aluminum ingots to a melting furnace, heat to 730-750℃, add 10% aluminum-silicon alloy and 10% aluminum-cerium alloy, stir for 10-20 minutes at a speed of 80-100 rpm, add magnesium ingots, reduce the speed to 60-80 rpm, stir for 4-6 minutes, refine for 12-15 minutes, let stand for 20-30 minutes to remove slag, cool to 700-720℃, place in a continuous casting machine with a diameter of 9.5-12 mm, cool down to obtain aluminum rod billets; Step C2: Load the aluminum rod billet into a heat treatment furnace, heat it to 560-570℃, hold it for 100-140 min, after holding, water quench it, transfer it to an aging furnace, heat it to 170-180℃, hold it for 6-7 h, and then place it in a continuous wire drawing machine with a cemented carbide texture drawing die, with a groove depth of 15-25 μm, a drawing speed of 8-12 m / s, lubricant cooling, and a diameter of 2.0-4.5 mm to obtain aluminum alloy wire; The mass ratio of the aluminum ingot, aluminum-silicon alloy, aluminum-cerium alloy and magnesium ingot is 1:0.042-0.043:0.014-0.016:0.008-0.

009.

10. A method for preparing aluminum-clad steel-cored aluminum stranded wire for use in highly corrosive coastal environments according to any one of claims 1-9, characterized in that, The specific steps of the preparation method are as follows: Step S1: Immerse the aluminum alloy wire in the passivation solution, heat it to 20-30℃, immerse for 1-3 minutes, drain for 10-20 seconds, rinse with deionized water, and dry in an oven to obtain the passivated aluminum alloy wire. Step S2: Place the aluminum-clad steel core in a frame-type stranding machine with a pitch ratio of 14-18, a stranding speed of 100-200 rpm, induction heating at a frequency of 10-20 kHz and a travel speed of 10-20 m / min, raising the temperature to 70-80℃. Add passivated aluminum alloy wire with a pitch ratio of 12-16, and add corrosion-inhibiting sealant at a temperature of 85-95℃ and an injection pressure of 0.1-0.3 MPa. After the conductor exits the stranding die, cool it to 20-30℃, then add anti-corrosion grease at a temperature of 55-65℃ and an injection pressure of 0.3-0.5 MPa. After injection, place the machine in an annular ultraviolet irradiation channel with a wavelength of 360-370 nm and an irradiation intensity of 200-400 mW / cm². 2 Irradiation time is 4-8 seconds. After irradiation, the temperature is reduced to 20-30℃ to obtain aluminum-clad steel core aluminum stranded wire.

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