Steel-cored aluminum stranded conductor for power transmission line

Abstract

The present application relates to steel core aluminum stranded conductor technical field, propose a kind of steel core aluminum stranded conductor for transmission line, including galvanized steel core and the aluminum wire of being stranded in the surface of galvanized steel core, the preparation process of galvanized steel core, including the following steps: after oil removal, washing and drying of steel wire, immerse in zinc liquid, after galvanizing cooling, obtain galvanized steel wire, after passivation, drying, stranded, obtain galvanized steel core;The passivation liquid used in the process of passivation is composed of the following mass percentage components: water-based acrylic resin 16%~22%, anionic surfactant 0.6%~1.2%, filler 2%~4%, silane coupling agent 1%~3%, the rest is water;Filler includes carrier load metal oxoacid salt.The above technical scheme solves the problem of insufficient corrosion resistance of the steel core aluminum stranded conductor in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel-cored aluminum stranded conductor, in particular to a steel-cored aluminum stranded conductor for power transmission line. BACKGROUND

[0002] As the core conductor material of high-voltage power transmission line, the steel-cored aluminum stranded conductor is widely used in various power transmission scenes such as plains, mountains and coastal areas. However, the defect of insufficient corrosion resistance has long restricted the safety and service life of the power transmission line. The steel-cored aluminum stranded conductor is easily corroded in the corrosive medium in the natural environment, such as coastal areas and industrial areas. In the structure of the steel-cored aluminum stranded conductor, the steel core bears the main mechanical tension. In order to improve its corrosion resistance, the industry generally adopts hot galvanizing or electroplating zinc process to coat the surface of the steel core, and then carries out passivation treatment after galvanizing. The passivation treatment forms a dense passivation film on the surface of the galvanized layer, closes the micropores and defects of the galvanized layer, and reduces the direct contact between the galvanized layer and the corrosive medium, thereby further enhancing the corrosion resistance of the galvanized steel core.

[0003] At present, the commonly used passivation agent in the industry mainly includes chromate passivation agent and chromium-free passivation agent. The chromium-free passivation agent meets the environmental protection requirements, but the passivation film formed by the existing products generally has problems such as insufficient density, poor adhesion, limited salt mist corrosion resistance, etc., and it is difficult to meet the long-term corrosion resistance protection requirements of the steel-cored aluminum stranded conductor in the use environment. Therefore, it is very important to develop a new type of passivation agent which is environmentally friendly and efficient, and can form a passivation film with high density, strong adhesion and excellent corrosion resistance on the surface of the galvanized steel core, so as to improve the corrosion resistance of the galvanized steel core and prolong the service life of the steel-cored aluminum stranded conductor, and ensure the safety and stability of power transmission. SUMMARY

[0004] The present application provides a steel-cored aluminum stranded conductor for power transmission line, which solves the problem of insufficient corrosion resistance of the steel-cored aluminum stranded conductor in the related art.

[0005] The technical scheme of the present application is as follows:

[0006] The present application provides a steel-cored aluminum stranded conductor for power transmission line, which includes a galvanized steel core and an aluminum wire stranded on the surface of the galvanized steel core. The preparation process of the galvanized steel core includes the following steps: after the steel wire is degreased, washed and dried, it is immersed in a zinc liquid, cooled after galvanizing, and a galvanized steel wire is obtained. The galvanized steel wire is passivated, dried and stranded to obtain a galvanized steel core.

[0007] The passivation liquid used in the passivation process is composed of the following components in mass percentage: water-based acrylic resin 16%~22%, anionic surfactant 0.6%~1.2%, filler 2%~4%, silane coupling agent 1%~3%, and the balance is water.

[0008] The filler comprises a carrier loaded metal oxyacid salt;

[0009] The carrier in the carrier loaded metal oxyacid salt comprises one of silica and diatomite;

[0010] The metal oxyacid salt in the carrier loaded metal oxyacid salt comprises one of tungstate and molybdate.

[0011] As a further technical solution, the carrier loaded metal oxyacid salt is composed of silica loaded sodium tungstate and diatomite loaded sodium molybdate with a mass ratio of 1-3:1.

[0012] The silica loaded sodium tungstate and diatomite loaded sodium molybdate are compounded and added into the passivation solution, and the corrosion resistance of the galvanized steel core after passivation is greatly improved; the zinc tungsten oxide precipitate and the molybdate complex are intertwined with each other during the formation process, forming a more compact protective film; the pore structures of silica and diatomite are different and complement each other, the mesoporous silica can adsorb smaller corrosion medium ions, while the macropores and mesopores of diatomite can help accommodate larger molecules or ion groups, thereby increasing the corrosion resistance of the galvanized steel core and improving the corrosion resistance of the steel core aluminum stranded wire.

[0013] As a further technical solution, the preparation method of the carrier loaded metal oxyacid salt comprises the following steps:

[0014] S1, the carrier is leached with a nitric acid solution, then washed with water until neutral, dried, ground, and an activated carrier is obtained;

[0015] S2, the metal oxyacid salt is added to water, and then the activated carrier is added, refluxed, filtered, and dried to obtain the carrier loaded metal oxyacid salt.

[0016] As a further technical solution, the molar concentration of the nitric acid solution is 0.15-0.25 mol / L.

[0017] As a further technical solution, the leaching is performed 2-3 times.

[0018] As a further technical solution, in step S1, the drying temperature is 100-120℃, and the time is 6-8h.

[0019] As a further technical solution, when the activated carrier is activated silica, the particle size of the activated silica is 1-2μm; when the activated carrier is activated diatomite, the particle size of the activated diatomite is 3-4μm.

[0020] As a further technical solution, the mass ratio of the metal oxyacid salt to water is 1:8-12.

[0021] As a further technical solution, the mass ratio of the metal oxoacid salt and the activated carrier is 1:3-5.

[0022] As a further technical solution, the temperature of the reflux reaction is 100-105℃, and the time is 4-5h.

[0023] As a further technical solution, the reflux reaction is accompanied by stirring, and the stirring rate is 200-300r / min.

[0024] As a further technical solution, in step S2, the drying temperature is 80-100℃, and the time is 10-15h.

[0025] As a further technical solution, the passivation temperature is 40-50℃, and the time is 10-12min.

[0026] As a further technical solution, the temperature of the zinc liquid is 420-450℃, and the time is 100-120s.

[0027] As a further technical solution, the cooling includes first-stage cooling, second-stage cooling, and third-stage cooling, and the cooling rates of the first-stage cooling, the second-stage cooling, and the third-stage cooling are different.

[0028] As a further technical solution, the first-stage cooling is cooling to 260-280℃ at a cooling rate of 18-20℃ / s, and holding for 10-15min;

[0029] The second-stage cooling is cooling to 180-200℃ at a cooling rate of 6-8℃ / s, and holding for 5-8min;

[0030] The third-stage cooling is cooling to room temperature at a cooling rate of 3-5℃ / s.

[0031] The present application can improve the tensile strength of the galvanized steel wire by controlling the cooling rate of three cooling time periods during the cooling process after galvanizing. The first cooling rate is 18-20 DEG C / s, which can form fine and uniform grain structure on the surface of the galvanized layer. The second cooling rate is 6-8 DEG C / s, which can promote the solidification and structure transformation of the galvanized layer, further refine the grain, and form uniform and dense zinc-iron alloy layer structure. The third cooling rate is 3-5 DEG C / s, which can further eliminate internal stress and improve the bonding force between the galvanized layer, zinc-iron alloy layer and the steel wire matrix, thereby improving the tensile strength of the galvanized steel wire and further improving the tensile strength of the steel core aluminum stranded wire.

[0032] As a further technical solution, the anionic surfactant includes one of sodium dodecyl benzene sulfonate and calcium dodecyl benzene sulfonate.

[0033] In the passivation solution, the anionic surfactant can reduce the surface tension of the passivation solution, ensure uniform coverage of the passivation solution, and improve the passivation effect. The anionic surfactant is one or more of conventional anionic surfactants, such as sodium dodecyl benzene sulfonate, calcium dodecyl benzene sulfonate, and sodium fatty alcohol polyoxyethylene ether sulfate. Preferably, the anionic surfactant is one of sodium dodecyl benzene sulfonate and calcium dodecyl benzene sulfonate.

[0034] As a further technical solution, the silane coupling agent includes one of silane coupling agent KH-550 and silane coupling agent KH-560.

[0035] In the passivation solution, the silane coupling agent enhances the bonding force between the film layer and the galvanized layer. The silane coupling agent can be one or more of conventional silane coupling agents, such as silane coupling agent KH-550, silane coupling agent KH-560, and silane coupling agent KH-792. Preferably, the silane coupling agent is one of silane coupling agent KH-550 and silane coupling agent KH-560.

[0036] The working principle and beneficial effects of the present application are as follows:

[0037] The application adds the carrier loaded metal oxyacid salt into the passivation solution to perform passivation treatment on the galvanized steel wire, and the obtained galvanized steel core has excellent corrosion resistance. When the metal oxyacid salt includes tungstate, the tungstate ions can react with the zinc ions dissolved from the surface of the galvanized layer to form a difficultly soluble zinc tungsten oxide precipitate on the surface of the galvanized layer; when the metal oxyacid salt includes molybdate, the molybdate ions can not only react with the zinc ions on the surface of the galvanized layer, but also can chemically react with the ferrous ions dissolved from the steel wire substrate to form a molybdate complex with good corrosion resistance on the surface of the galvanized steel wire, and finally form a dense protective film to hinder the contact between the corrosion medium and the galvanized layer. Meanwhile, the metal oxyacid salt is loaded on the carrier, which not only increases the dispersion stability, but also can play a slow release role, thereby significantly prolonging the corrosion resistance life of the galvanized steel core. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the application will be clearly and completely described below in combination with the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor also fall within the protection scope of the application.

[0039] In the following examples and comparative examples,

[0040] The aqueous acrylic resin is NeoCryl A614 from the company Covestro;

[0041] The steel wire material is 45 steel.

[0042] Example 1

[0043] The preparation process of the galvanized steel core includes the following steps: after the steel wire is degreased, washed and dried, it is immersed in a zinc liquid at 420℃ for 120s, cooled to 280℃ at a cooling rate of 22℃ / s, kept for 10min, then cooled to 200℃ at a cooling rate of 10℃ / s, kept for 5min, finally cooled to room temperature at a cooling rate of 6℃ / s, to obtain a galvanized steel wire, which is placed in a passivation solution at 40℃ for passivation for 12min, dried at 120℃ for 12min, and then 19 steel wires are stranded to obtain a galvanized steel core.

[0044] The passivation solution is composed of the following components in mass percentage: 16% of the aqueous acrylic resin, 0.6% of sodium dodecyl benzene sulfonate, 2% of the filler, 1% of the silane coupling agent KH-550, and the balance of water;

[0045] The filler is a mixture of silica loaded sodium tungstate and diatomite loaded sodium molybdate in a mass ratio of 1:1;

[0046] A method for preparing silica supported sodium tungstate, comprising the following steps:

[0047] The silica is leached with 0.15 mol / L nitric acid solution for 3 times, washed with water to neutral, dried at 100℃ for 8h, ground, and activated silica with a particle size of 1μm is obtained;

[0048] The sodium tungstate is added into water (the mass ratio of sodium tungstate to water is 1:8), and the activated silica is added (the mass ratio of sodium tungstate to activated silica is 1:3), heated to 100℃, refluxed at 300r / min for 5h, filtered, dried at 80℃ for 15h, and silica supported sodium tungstate is obtained;

[0049] A method for preparing diatomite supported sodium molybdate, comprising the following steps:

[0050] The diatomite is leached with 0.15 mol / L nitric acid solution for 3 times, washed with water to neutral, dried at 100℃ for 8h, ground, and activated diatomite with a particle size of 3μm is obtained;

[0051] The sodium molybdate is added into water (the mass ratio of sodium molybdate to water is 1:8), and the activated diatomite is added (the mass ratio of sodium molybdate to activated diatomite is 1:3), heated to 100℃, refluxed at 300r / min for 5h, filtered, dried at 80℃ for 15h, and diatomite supported sodium tungstate is obtained;

[0052] A method for preparing a steel-cored aluminum strand for power transmission line, comprising the following steps: 26 nickel-plated phosphorus alloy aluminum wires are twisted in one layer on the surface of a galvanized steel core to obtain a steel-cored aluminum strand for power transmission line.

[0053] Example 2

[0054] A preparation process of a galvanized steel core, comprising the following steps: after the steel wire is degreased, washed with water and dried, it is immersed in a zinc liquid at 450℃ for 100s, cooled to 260℃ at a cooling rate of 22℃ / s, kept for 15min, then cooled to 180℃ at a cooling rate of 10℃ / s, kept for 8min, finally cooled to room temperature at a cooling rate of 6℃ / s, to obtain a galvanized steel wire, the galvanized steel wire is placed in a passivation liquid at 50℃ for passivation for 10min, dried at 120℃ for 12min, and 19 steel wires are twisted to obtain a galvanized steel core;

[0055] The passivation liquid is composed of the following components in mass percentage: water-based acrylic resin 22%, calcium dodecylbenzenesulfonate 1.2%, filler 4%, silane coupling agent KH-560 3%, and the balance is water;

[0056] The filler is silica supported sodium tungstate and diatomite supported sodium molybdate in a mass ratio of 1:1;

[0057] A method for preparing silica supported sodium tungstate, comprising the following steps:

[0058] The silica is rinsed twice with a 0.25 mol / L nitric acid solution, washed with water until neutral, dried at 120℃ for 6h, ground, and activated silica with a particle size of 2μm is obtained;

[0059] The sodium tungstate is added to water (the mass ratio of sodium tungstate to water is 1:12), and the activated silica is added (the mass ratio of sodium tungstate to activated silica is 1:5), heated to 105℃, refluxed at 200r / min for 4h, filtered, and dried at 100℃ for 10h to obtain silica supported sodium tungstate;

[0060] A method for preparing diatomite supported sodium molybdate, comprising the following steps:

[0061] The diatomite is rinsed twice with a 0.25 mol / L nitric acid solution, washed with water until neutral, dried at 120℃ for 6h, ground, and activated diatomite with a particle size of 4μm is obtained;

[0062] The sodium molybdate is added to water (the mass ratio of sodium molybdate to water is 1:12), and the activated diatomite is added (the mass ratio of sodium molybdate to activated diatomite is 1:5), heated to 105℃, refluxed at 200r / min for 4h, filtered, and dried at 100℃ for 10h to obtain diatomite supported sodium molybdate;

[0063] A method for preparing a steel-cored aluminum strand for power transmission lines, comprising the following steps: 26 nickel-plated phosphorus alloy aluminum wires are twisted in one layer on the surface of a galvanized steel core to obtain a steel-cored aluminum strand for power transmission lines.

[0064] Example 3

[0065] A preparation process of a galvanized steel core, comprising the following steps: after the steel wire is degreased, washed with water and dried, it is immersed in a zinc liquid at 440℃ for 110s, cooled to 270℃ at a cooling rate of 22℃ / s, kept at 270℃ for 12min, then cooled to 190℃ at a cooling rate of 10℃ / s, kept at 190℃ for 6min, and finally cooled to room temperature at a cooling rate of 6℃ / s to obtain a galvanized steel wire, the galvanized steel wire is placed in a passivation liquid at 45℃ for passivation for 11min, dried at 120℃ for 12min, and 19 steel wires are twisted to obtain a galvanized steel core;

[0066] The passivation liquid is composed of the following components in mass percentage: water-based acrylic resin 19%, calcium dodecylbenzenesulfonate 0.8%, filler 3%, silane coupling agent KH-550 2%, and the balance is water;

[0067] The filler is silica supported sodium tungstate and diatomite supported sodium molybdate in a mass ratio of 1:1;

[0068] A preparation method of silica supported sodium tungstate comprises the following steps:

[0069] The silica is leached with 0.2 mol / L nitric acid solution for 3 times, washed with water to neutral, dried at 110℃ for 7h, ground, and activated silica with a particle size of 1μm is obtained;

[0070] The sodium tungstate is added into water (the mass ratio of sodium tungstate to water is 1:10), and the activated silica is added (the mass ratio of sodium tungstate to activated silica is 1:4), heated to 105℃, refluxed at 250r / min for 4h, filtered, dried at 90℃ for 12h, and silica supported sodium tungstate is obtained;

[0071] A preparation method of diatomite supported sodium molybdate comprises the following steps:

[0072] The diatomite is leached with 0.2 mol / L nitric acid solution for 3 times, washed with water to neutral, dried at 110℃ for 7h, ground, and activated diatomite with a particle size of 3μm is obtained;

[0073] The sodium molybdate is added into water (the mass ratio of sodium molybdate to water is 1:10), and the activated diatomite is added (the mass ratio of sodium molybdate to activated diatomite is 1:4), heated to 105℃, refluxed at 250r / min for 4h, filtered, dried at 90℃ for 12h, and diatomite supported sodium molybdate is obtained;

[0074] A preparation method of a steel-cored aluminum strand for power transmission line comprises the following steps: 26 nickel-plated phosphorus alloy aluminum wires are twisted in one layer on the surface of a galvanized steel core to obtain a steel-cored aluminum strand for power transmission line.

[0075] Example 4

[0076] The difference between this example and example 3 is that the fillers are silica supported sodium tungstate and diatomite supported sodium molybdate with a mass ratio of 2:1.

[0077] Example 5

[0078] The difference between this example and example 3 is that the fillers are silica supported sodium tungstate and diatomite supported sodium molybdate with a mass ratio of 3:1.

[0079] Example 6

[0080] The difference between this embodiment and embodiment 4 is only in the preparation process of the galvanized steel core, which comprises the following steps: after the steel wire is degreased, washed and dried, it is immersed in a zinc solution at 440℃ for 110s, cooled to 270℃ at a cooling rate of 20℃ / s, kept for 12min, then cooled to 190℃ at a cooling rate of 8℃ / s, kept for 6min, and finally cooled to room temperature at a cooling rate of 5℃ / s, to obtain a galvanized steel wire, which is placed in a passivation solution at 45℃ for passivation for 11min, dried at 120℃ for 12min, and then 19 steel wires are stranded to obtain a galvanized steel core.

[0081] Embodiment 7

[0082] The difference between this embodiment and embodiment 4 is only in the preparation process of the galvanized steel core, which comprises the following steps: after the steel wire is degreased, washed and dried, it is immersed in a zinc solution at 440℃ for 110s, cooled to 270℃ at a cooling rate of 20℃ / s, kept for 12min, then cooled to 190℃ at a cooling rate of 8℃ / s, kept for 6min, and finally cooled to room temperature at a cooling rate of 5℃ / s, to obtain a galvanized steel wire, which is placed in a passivation solution at 45℃ for passivation for 11min, dried at 120℃ for 12min, and then 19 steel wires are stranded to obtain a galvanized steel core.

[0083] Embodiment 8

[0084] The difference between this embodiment and embodiment 4 is only in the preparation process of the galvanized steel core, which comprises the following steps: after the steel wire is degreased, washed and dried, it is immersed in a zinc solution at 440℃ for 110s, cooled to 270℃ at a cooling rate of 20℃ / s, kept for 12min, then cooled to 190℃ at a cooling rate of 8℃ / s, kept for 6min, and finally cooled to room temperature at a cooling rate of 5℃ / s, to obtain a galvanized steel wire, which is placed in a passivation solution at 45℃ for passivation for 11min, dried at 120℃ for 12min, and then 19 steel wires are stranded to obtain a galvanized steel core.

[0085] Embodiment 9

[0086] The difference between this embodiment and embodiment 3 is only that the filler is silica supported sodium tungstate.

[0087] Embodiment 10

[0088] The difference between this embodiment and embodiment 3 is only that the filler is diatomite supported sodium molybdate.

[0089] Embodiment 11

[0090] The difference between this embodiment and embodiment 3 is only that the filler is silica supported sodium tungstate and silica supported sodium molybdate in a mass ratio of 1:1;

[0091] A method for preparing silica supported sodium molybdate, comprising the following steps:

[0092] The silica is leached with a 0.2 mol / L nitric acid solution for 3 times, and then washed with water until neutral, and dried at 110°C for 7h to obtain activated silica with a particle size of 1um;

[0093] The sodium molybdate is added to water (the mass ratio of sodium molybdate to water is 1:10), and then the activated silica (the mass ratio of sodium molybdate to activated silica is 1:4) is added, and the temperature is raised to 105°C, and the reaction is carried out under reflux at 250r / min for 4h, and then filtered and dried at 90°C for 12h to obtain silica supported sodium molybdate.

[0094] Comparative Example 1

[0095] The difference between this comparative example and Example 3 is only that the filler is sodium tungstate.

[0096] Comparative Example 2

[0097] The difference between this comparative example and Example 3 is only that the filler is sodium molybdate.

[0098] The galvanized steel cores prepared in Examples 1-5, Examples 9-11 and Comparative Examples 1-2 are subjected to corrosion resistance testing according to the following method:

[0099] According to the neutral salt spray test standard in GB / T 10125 2021 "Artificial Atmosphere Corrosion Test Salt Spray Test", the spraying is 6wt% NaCl aqueous solution, the temperature is 40°C, every 15min, spray for 15min, observe the corrosion of the sample surface, record the time when the sample surface starts to corrode;

[0100] The test results are shown in Table 1:

[0101] Table 1 Performance test results of galvanized steel cores prepared in Examples 1-5, Examples 9-11 and Comparative Examples 1-2

[0102]

[0103] 1. Compared with Examples 1-5, Examples 9-11 and Comparative Examples 1-2, the salt spray resistance time of the galvanized steel cores prepared in Examples 1-5, Examples 9-11 is much higher than that of Comparative Examples 1-2, which shows that loading the carrier (one of silica and diatomite) with metal oxyacid salt (one of tungstate and molybdate) and adding it to the passivator can greatly improve the corrosion resistance of the steel core aluminum strand after passivation treatment.

[0104] 2. Compared with Examples 3-5 and Examples 9-11, the salt spray resistance time of the galvanized steel core prepared in Example 4 is longer than that of Examples 3, 5 and Examples 9-11. This indicates that when the carrier-loaded metal oxyacid salt is a combination of silica-loaded sodium tungstate and diatomaceous earth-loaded sodium molybdate, and the mass ratio of silica-loaded sodium tungstate to diatomaceous earth-loaded sodium molybdate is 2:1, the corrosion resistance of the galvanized steel core after passivation treatment is further improved.

[0105] The tensile strength of the steel-cored aluminum stranded wires obtained in Examples 4 and 6-8 was tested according to the following method:

[0106] Refer to GB / T 228.1 2021 "Metallic materials, tensile testing - Part 1: Test method at room temperature" determines tensile strength, wherein the separation speed of the tensile testing machine clamp is 50 mm / min;

[0107] The test results are shown in Table 2:

[0108] Table 2. Test results of tensile strength of steel-cored aluminum stranded wires prepared in Examples 4 and 6-8

[0109]

[0110] Compared with Examples 4 and 6-8, the tensile strength of the steel-cored aluminum stranded wires prepared in Examples 6-7 is higher than that in Examples 4 and 8. This indicates that by controlling the cooling rate of the three cooling stages during the preparation of the galvanized steel core, with the first cooling rate at 18-20℃ / s, the second cooling rate at 6-8℃ / s, and the third cooling rate at 3-5℃ / s, the tensile strength of the galvanized steel core is further improved, thereby further improving the tensile strength of the steel-cored aluminum stranded wire.

[0111] 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 steel-cored aluminum stranded wire for power transmission lines, characterized in that, The product includes a galvanized steel core and aluminum wire stranded on the surface of the galvanized steel core. The preparation process of the galvanized steel core includes the following steps: after degreasing, washing and drying the steel wire, immersing it in zinc liquid, galvanizing it and cooling it to obtain galvanized steel wire, and then passivating, drying and stranding the galvanized steel wire to obtain the galvanized steel core. The passivation solution used in the passivation process consists of the following components by mass percentage: 16%~22% aqueous acrylic resin, 0.6%~1.2% anionic surfactant, 2%~4% filler, 1%~3% silane coupling agent, and the balance being water; The filler comprises a carrier-supported metal oxyacid salt; The carrier-loaded metal oxyacid salt is composed of sodium tungstate supported by silica and sodium molybdate supported by diatomite in a mass ratio of 1 to 3:

1. The cooling process includes a first stage of cooling, a second stage of cooling, and a third stage of cooling, with different cooling rates for the first stage of cooling, the second stage of cooling, and the third stage of cooling. The first stage of cooling is as follows: cooling to 260~280℃ at a cooling rate of 18~20℃ / s, and holding at that temperature for 10~15min; The second stage of cooling is as follows: the temperature is reduced to 180-200℃ at a rate of 6-8℃ / s, and held for 5-8 minutes. The third stage of cooling involves reducing the temperature to room temperature at a rate of 3~5℃ / s.

2. The steel-cored aluminum stranded wire for transmission lines according to claim 1, characterized in that, The method for preparing the metal oxyacid salt supported on the carrier includes the following steps: S1. Rinse the carrier with nitric acid solution, then wash with water until neutral, dry, and grind to obtain the activated carrier; S2. Add the metal oxyacid salt to water, then add the activated support, reflux, filter, and dry to obtain the support-loaded metal oxyacid salt.

3. The steel-cored aluminum stranded wire for transmission lines according to claim 2, characterized in that, The molar concentration of the nitric acid solution is 0.15~0.25 mol / L.

4. The steel-cored aluminum stranded wire for transmission lines according to claim 2, characterized in that, The mass ratio of the metal oxyacid salt to water is 1:8~12; The mass ratio of the metal oxyacid salt to the activation support is 1:3~5; The reflux reaction is carried out at a temperature of 100-105°C for 4-5 hours.

5. The steel-cored aluminum stranded wire for transmission lines according to claim 1, characterized in that, The passivation temperature is 40~50℃, and the time is 10~12min; The temperature of the zinc liquid is 420~450℃, and the time is 100~120s.

6. The steel-cored aluminum stranded wire for transmission lines according to claim 1, characterized in that, The anionic surfactant includes one of sodium dodecylbenzenesulfonate and calcium dodecylbenzenesulfonate.

7. The steel-cored aluminum stranded wire for transmission lines according to claim 1, characterized in that, The silane coupling agent includes one of silane coupling agent KH-550 and silane coupling agent KH-560.

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