Corrosion-resistant overhead conductor and preparation method thereof

Abstract

The invention relates to the technical field of power grid safety guarantee, and provides a corrosion-resistant overhead conductor and a preparation method thereof.The corrosion-resistant overhead conductor is provided with a force bearing part and a stranded aluminum conductor arranged on the outer side of the force bearing part, and the outermost layer of the stranded aluminum conductor is provided with a gradient composite film with continuously-changed components and structures. The gradient composite film comprises a transition layer, a protective layer and a functional layer from inside to outside, the transition layer is composed of an amorphous phase and an alpha-Al2O3 phase, the protective layer is composed of a t-ZrO2 phase, an m-ZrO2 phase and a Y2O3 phase, and the surface functional layer is composed of a t-ZrO2 phase and an m-ZrO2 phase. According to the corrosion-resistant overhead conductor and the preparation method thereof, a gradient composite film with continuous gradient change of components and structures can be constructed through construction of a gradient concentration electrolyte system and in-situ growth, so that the corrosion resistance of the surface of the aluminum conductor is remarkably improved; and the gradient composite film is prevented from peeling off or losing efficacy due to external factors in the long-term use process, and is suitable for industrial continuous production.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid security, and in particular to a corrosion-resistant overhead conductor and a preparation method thereof. Background Art

[0002] Overhead conductors, as a key component of the power transmission network, carry the vital function of long-distance, high-capacity power transmission. A typical overhead conductor structure consists of a steel core (such as galvanized steel strands) and an outer layer of stranded aluminum conductors. The aluminum conductor serves as the primary conductive medium, and its performance directly impacts the reliability and service life of the transmission line. Stranded aluminum conductors face multiple corrosion threats during service: 1. Atmospheric corrosion (such as acid rain and salt spray); 2. Electrochemical corrosion (from dissimilar metal contact or stray currents); and 3. Localized corrosion caused by fretting. These corrosion processes not only reduce the conductor's cross-sectional area and increase its resistance (according to IEC 61089, an increase in resistance exceeding 10% due to corrosion requires replacement), but can also lead to serious accidents such as strand breakage. Particularly in corrosive environments such as coastal and industrial areas, approximately 78% of overhead conductor failures are due to corrosion damage to the outer aluminum conductor.

[0003] Chinese patent publication number CN 115938691A discloses a method for preparing an overhead wire with a corrosion-resistant ceramic film layer, and Chinese patent publication number CN115841887 A discloses a corrosion-resistant overhead wire. These two solutions have the following shortcomings in practical applications: 1. The film layer structure is simple, with the main component being amorphous Al2O3. In order to maintain a certain degree of flexibility, the film layer thickness is ≤15μm. When faced with a corrosive environment, the inherent stability and corrosion resistance of this film layer structure are very weak. 2. The preparation method of first forming a ceramic film layer on a single aluminum wire and then twisting it significantly increases the process complexity and cost. During the twisting process, the spiral torsional deformation of the single aluminum wire, the friction between adjacent aluminum wires, and the friction between the aluminum wire and the twisting mold will seriously damage the film layer on the aluminum wire, and further reduce the bonding strength between the film layer and the conductor substrate.

[0004] Therefore, how to construct a composite film layer with continuous gradient changes in composition and structure on the surface of overhead conductors, so that the composite film layer can be highly strongly bonded to the conductor substrate while providing excellent corrosion resistance and reducing process costs, is a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0005] In view of this, in order to overcome the deficiencies of the prior art, the present invention aims to provide a corrosion-resistant overhead conductor and a method for preparing the same.

[0006] According to a first aspect of the present invention, there is provided a corrosion-resistant overhead conductor comprising a load-bearing member and a stranded aluminum conductor arranged outside the load-bearing member, wherein the outermost layer of the stranded aluminum conductor comprises a gradient composite film having a continuously changing composition and structure, the gradient composite film comprising, from the inside to the outside, a transition layer, a protective layer and a functional layer, wherein the transition layer is composed of an amorphous phase and an α-Al2O3 phase, the protective layer is composed of a t-ZrO2 phase, an m-ZrO2 phase and a Y2O3 phase, and the surface functional layer is composed of a t-ZrO2 phase and an m-ZrO2 phase.

[0007] Optionally, in the corrosion-resistant overhead conductor of the present invention, the Zr element content of the transition layer decreases gradually from 100at% to 30-35at% from the inside to the outside, the content of the Y2O3 phase in the protective layer decreases gradually from 8-9mol% to 2-4mol% from the inside to the outside, and the ratio of the t-ZrO2 phase and the m-ZrO2 phase in the surface functional layer is 1.2-2.6:1.

[0008] According to a second aspect of the present invention, a method for preparing a corrosion-resistant overhead conductor is provided, the method comprising: constructing a gradient concentration electrolyte system, and in situ constructing a gradient composite film with continuously changing composition and structure on the surface of a stranded aluminum conductor by pulse-modulated plasma electrolytic oxidation treatment in the gradient concentration electrolyte system.

[0009] Optionally, in the preparation method of the corrosion-resistant overhead conductor of the present invention, a gradient concentration electrolyte system is constructed by dynamically supplying electrolytes of different components in different zones. The gradient concentration electrolyte system consists of an electrolyte in the near-electrode area, an electrolyte in the intermediate transition area, and an electrolyte in the far-electrode area. The electrolyte in the near-electrode area, the electrolyte in the intermediate transition area, and the electrolyte in the far-electrode area are dynamically supplied in a volume ratio of 1:0.5:0.2.

[0010] Optionally, in the preparation method of the corrosion-resistant overhead wire of the present invention, the electrolyte in the near-electrode area includes 0.3-0.6 mol / L of Zr(NO3)4 and 0.05-0.1 mol / L of Y(NO3)3, the electrolyte in the intermediate transition area includes 0.1-0.3 mol / L of Zr(NO3)4 and 0.02-0.05 mol / L of Y(NO3)3, and the electrolyte in the far-electrode area includes 0.05-0.1 mol / L of Zr(NO3)4 and 0.01-0.02 mol / L of Y(NO3)3.

[0011] Optionally, in the method for preparing the corrosion-resistant overhead conductor of the present invention, when the surface of the stranded aluminum conductor is subjected to pulse-modulated plasma electrolytic oxidation treatment in a gradient concentration electrolyte system, three-stage discharge parameter control is used to sequentially form the transition layer, protective layer and functional layer in the gradient composite film.

[0012] Optionally, in the method for preparing the corrosion-resistant overhead conductor of the present invention, a transition layer, a protective layer, and a functional layer in the gradient composite film are sequentially formed by controlling three-stage discharge parameters, including:

[0013] During the transition layer formation stage, the discharge voltage is 300-350V, the discharge frequency is 100-150Hz, the discharge duty cycle is 30-40%, and the discharge duration is 180-300s;

[0014] During the protective layer growth stage, the discharge voltage is 350-400V, the discharge frequency is 150-200Hz, the discharge duty cycle is 40-50%, and the discharge duration is 300-480s;

[0015] During the functional layer regulation stage, the discharge voltage is 250-300V, the discharge frequency is 50-100Hz, the discharge duty cycle is 20-30%, and the discharge duration is 120-180s.

[0016] Optionally, in the method for preparing the corrosion-resistant overhead conductor of the present invention, before constructing the gradient composite film on the surface of the twisted aluminum conductor, the surface of the twisted aluminum conductor is sandblasted using α-Al2O3 abrasive with a particle size of 80-120 μm, the sandblasting pressure is 0.4-0.8 MPa, and the surface roughness Ra of the twisted aluminum conductor after sandblasting is 3.2-6.4 μm.

[0017] Optionally, in the method for preparing the corrosion-resistant overhead conductor of the present invention, after constructing a gradient composite film on the surface of the twisted aluminum conductor, the aluminum conductor having the gradient composite film on the surface is subjected to a step-curing treatment in a vacuum environment.

[0018] Optionally, in the preparation method of the corrosion-resistant overhead conductor of the present invention, in a vacuum environment, the aluminum conductor with a gradient composite film is heated to 80°C at a heating rate of 2°C / min, kept warm for 20 minutes, and then heated to 125°C at a heating rate of 5°C / min and kept warm for 35 minutes.

[0019] The corrosion-resistant overhead conductor and the preparation method thereof of the present invention have the following beneficial technical effects:

[0020] 1. By constructing a gradient concentration electrolyte system and in-situ growth, a gradient composite membrane with continuous gradient changes in composition and structure is constructed, which includes a transition layer, a protective layer and a functional layer from the inside to the outside.

[0021] 2. The gradient composite film significantly improves the corrosion resistance of the aluminum conductor surface, allowing the corrosion-resistant overhead wires to operate stably for a long time in complex corrosive environments such as coastal salt spray and industrial acid rain, effectively solving the problem of existing overhead wires being prone to corrosion and failure in harsh environments.

[0022] 3. The high-strength combination of the gradient composite film and the aluminum conductor matrix ensures that the gradient composite film will not peel off or fail due to external factors during long-term use, further protecting the corrosion resistance of the conductor.

[0023] 4. Pulsed plasma electrolytic oxidation treatment is used, and a gradient concentration electrolyte system is established by dynamically supplying different electrolyte components in different zones, enabling the in-situ construction of a gradient composite membrane. This method offers advantages such as simplicity, ease of operation, and low cost. It is also suitable for industrial continuous production and readily applicable, meeting the needs of large-scale production of corrosion-resistant overhead conductors. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 This is a flowchart illustrating a method for preparing a corrosion-resistant overhead conductor according to Example 1 of the present invention;

[0026] Figure 2 This is a SEM image of a gradient composite membrane prepared according to Example 2 of the present invention;

[0027] Figure 3 XRD phase quantitative diagrams of the gradient composite films prepared according to Examples 2 to 6 of the present invention;

[0028] Figure 4 XRD phase grain size diagram of the gradient composite film prepared according to Examples 2 to 6 of the present invention;

[0029] Figure 5 XRD phase distribution diagram of the gradient composite membrane prepared according to Examples 2 to 6 of the present invention;

[0030] Figure 6 is a graph of corrosion rates calculated based on the corrosion weight loss of inventive examples 2 to 6 and the control group;

[0031] Figure 7 This is a SEM morphology image of the corrosion-resistant overhead wire prepared according to Example 3 of the invention after a 500-hour salt spray test;

[0032] Figure 8 This is a SEM morphology image of the corrosion-resistant overhead wire prepared according to Example 4 of the invention after a 500-hour salt spray test;

[0033] Figure 9 This is the SEM morphology of the overhead wire prepared according to the control group after 500h salt spray test. DETAILED DESCRIPTION

[0034] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0035] It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments may be combined with each other; and, based on the embodiments in this disclosure, all other embodiments obtained by persons of ordinary skill in the art without creative work are within the scope of protection of this disclosure.

[0036] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on this disclosure, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this apparatus and / or practice this method.

[0037] Example 1

[0038] Figure 1 FIG. 1 is a flow chart illustrating a method for preparing a corrosion-resistant overhead conductor according to Example 1 of the present invention. Figure 1 As shown, in this embodiment, the method for preparing the corrosion-resistant overhead conductor includes:

[0039] Step S1: preparing an overhead conductor having a load-bearing member and a stranded aluminum conductor.

[0040] As an optional example, in this embodiment, the overhead conductor can select specific load-bearing components and stranded aluminum conductors based on actual line parameters. For example, the load-bearing components can be galvanized steel strands, Invar cores, or ultra-high-strength steel cores or strands. The stranded aluminum conductor consists of multiple layers of aluminum monofilaments regularly twisted together on the outside of the load-bearing components. The aluminum monofilaments can be made of electrical aluminum, 6201 aluminum alloy, or soft aluminum materials with a conductivity greater than 62.5% IACS.

[0041] Step S2: Constructing a gradient concentration electrolyte system.

[0042] In this embodiment, a gradient concentration electrolyte system is constructed by dynamically supplying electrolytes of different components in different zones. The gradient concentration electrolyte system consists of an electrolyte in the near-electrode area, an electrolyte in the intermediate transition area, and an electrolyte in the far-electrode area. The electrolyte in the near-electrode area, the electrolyte in the intermediate transition area, and the electrolyte in the far-electrode area are dynamically supplied in a volume ratio of 1:0.5:0.2.

[0043] As an optional example, in this embodiment, the electrolyte in the near-electrode region includes 0.3-0.6 mol / L of Zr(NO3)4 and 0.05-0.1 mol / L of Y(NO3)3, the electrolyte in the intermediate transition region includes 0.1-0.3 mol / L of Zr(NO3)4 and 0.02-0.05 mol / L of Y(NO3)3, and the electrolyte in the far-electrode region includes 0.05-0.1 mol / L of Zr(NO3)4 and 0.01-0.02 mol / L of Y(NO3)3.

[0044] Step S3: In-situ constructing a gradient composite film with continuously changing composition and structure on the surface of the stranded aluminum conductor through pulse modulation plasma electrolytic oxidation treatment in a gradient concentration electrolyte system.

[0045] In this embodiment, before constructing the gradient composite film on the surface of the stranded aluminum conductor, the surface of the stranded aluminum conductor is sandblasted using α-Al2O3 abrasive with a particle size of 80-120 μm. The sandblasting pressure is 0.4-0.8 MPa. After sandblasting, the surface roughness Ra of the stranded aluminum conductor is 3.2-6.4 μm.

[0046] In this embodiment, when the surface of the stranded aluminum conductor is subjected to pulse-modulated plasma electrolytic oxidation treatment in a gradient concentration electrolyte system, a three-stage discharge parameter control is adopted to sequentially form the transition layer, the protective layer and the functional layer in the gradient composite film.

[0047] As an optional example, this embodiment adopts three-stage discharge parameter control to sequentially form a transition layer, a protective layer and a functional layer in the gradient composite film. During the transition layer formation stage, the discharge voltage is 300-350V, the discharge frequency is 100-150Hz, the discharge duty cycle is 30-40%, and the discharge duration is 180-300s; during the protective layer growth stage, the discharge voltage is 350-400V, the discharge frequency is 150-200Hz, the discharge duty cycle is 40-50%, and the discharge duration is 300-480s; during the functional layer regulation stage, the discharge voltage is 250-300V, the discharge frequency is 50-100Hz, the discharge duty cycle is 20-30%, and the discharge duration is 120-180s.

[0048] After forming a gradient composite film on the surface of the stranded aluminum conductor, the aluminum conductor with the gradient composite film is subjected to a step-by-step curing process in a vacuum environment. For example, in a vacuum environment, the aluminum conductor with the gradient composite film is heated to 80°C at a heating rate of 2°C / min, held at this temperature for 20 minutes, and then heated to 125°C at a heating rate of 5°C / min and held at this temperature for 35 minutes.

[0049] In the corrosion-resistant overhead wire of this embodiment, the outermost layer of the stranded aluminum conductor has a gradient composite film with continuously changing composition and structure, and the gradient composite film includes a transition layer, a protective layer and a functional layer from the inside to the outside.

[0050] Example 2

[0051] Before constructing the gradient composite film on the surface of the stranded aluminum conductor, the surface of the stranded aluminum conductor was sandblasted with α-Al2O3 abrasive with a particle size of 100 μm and a sandblasting pressure of 0.6 MPa. After sandblasting, the surface roughness Ra of the stranded aluminum conductor was 4.8 μm.

[0052] A gradient concentration electrolyte system is constructed by dynamically supplying electrolytes of different components in different zones. The gradient concentration electrolyte system consists of an electrolyte in the near-electrode zone, an electrolyte in the intermediate transition zone, and an electrolyte in the far-electrode zone. The electrolyte in the near-electrode zone, the electrolyte in the intermediate transition zone, and the electrolyte in the far-electrode zone are dynamically supplied in a volume ratio of 1:0.5:0.2. The electrolyte in the near-electrode zone includes 0.45 mol / L Zr(NO3)4 and 0.08 mol / L Y(NO3)3, the electrolyte in the intermediate transition zone includes 0.2 mol / L Zr(NO3)4 and 0.04 mol / L Y(NO3)3, and the electrolyte in the far-electrode zone includes 0.08 mol / L Zr(NO3)4 and 0.015 mol / L Y(NO3)3.

[0053] When the surface of the stranded aluminum conductor is subjected to pulse-modulated plasma electrolytic oxidation treatment in a gradient concentration electrolyte system, a three-stage discharge parameter control is adopted to sequentially form the transition layer, protective layer and functional layer in the gradient composite film. In the transition layer formation stage, the discharge voltage is 320V, the discharge frequency is 120Hz, the discharge duty cycle is 35%, and the discharge duration is 240s; in the protective layer growth stage, the discharge voltage is 380V, the discharge frequency is 180Hz, the discharge duty cycle is 45%, and the discharge duration is 360s; in the functional layer regulation stage, the discharge voltage is 280V, the discharge frequency is 80Hz, the discharge duty cycle is 25%, and the discharge duration is 150s.

[0054] After constructing a gradient composite film on the surface of the twisted aluminum conductor, the aluminum conductor with the gradient composite film was heated to 80°C at a heating rate of 2°C / min in a vacuum environment. After being kept warm for 20 minutes, the temperature was increased to 125°C at a heating rate of 5°C / min and kept warm for 35 minutes.

[0055] Example 3

[0056] Before constructing the gradient composite film on the surface of the stranded aluminum conductor, the surface of the stranded aluminum conductor was sandblasted with α-Al2O3 abrasive with a particle size of 80 μm and a sandblasting pressure of 0.4 MPa. After sandblasting, the surface roughness Ra of the stranded aluminum conductor was 3.2 μm.

[0057] A gradient concentration electrolyte system is constructed by dynamically supplying electrolytes of different components in different zones. The gradient concentration electrolyte system consists of an electrolyte in the near-electrode zone, an electrolyte in the intermediate transition zone, and an electrolyte in the far-electrode zone. The electrolyte in the near-electrode zone, the electrolyte in the intermediate transition zone, and the electrolyte in the far-electrode zone are dynamically supplied in a volume ratio of 1:0.5:0.2. The electrolyte in the near-electrode zone includes 0.3 mol / L Zr(NO3)4 and 0.05 mol / L Y(NO3)3, the electrolyte in the intermediate transition zone includes 0.1 mol / L Zr(NO3)4 and 0.02 mol / L Y(NO3)3, and the electrolyte in the far-electrode zone includes 0.05 mol / L Zr(NO3)4 and 0.01 mol / L Y(NO3)3.

[0058] When the surface of the stranded aluminum conductor is subjected to pulse-modulated plasma electrolytic oxidation treatment in a gradient concentration electrolyte system, a three-stage discharge parameter control is used to sequentially form the transition layer, protective layer and functional layer in the gradient composite film. In the transition layer formation stage, the discharge voltage is 300 V, the discharge frequency is 100 Hz, the discharge duty cycle is 30%, and the discharge duration is 180 s; in the protective layer growth stage, the discharge voltage is 350 V, the discharge frequency is 150 Hz, the discharge duty cycle is 40%, and the discharge duration is 300 s; in the functional layer regulation stage, the discharge voltage is 250 V, the discharge frequency is 50 Hz, the discharge duty cycle is 20%, and the discharge duration is 120 s.

[0059] After constructing a gradient composite film on the surface of the twisted aluminum conductor, the aluminum conductor with the gradient composite film was heated to 80°C at a heating rate of 2°C / min in a vacuum environment. After being kept warm for 20 minutes, the temperature was increased to 125°C at a heating rate of 5°C / min and kept warm for 35 minutes.

[0060] Example 4

[0061] Before constructing the gradient composite film on the surface of the stranded aluminum conductor, the surface of the stranded aluminum conductor was sandblasted with α-Al2O3 abrasive with a particle size of 120 μm and a sandblasting pressure of 0.8 MPa. After sandblasting, the surface roughness Ra of the stranded aluminum conductor was 6.4 μm.

[0062] A gradient concentration electrolyte system is constructed by dynamically supplying electrolytes of different components in different zones. The gradient concentration electrolyte system consists of an electrolyte in the near-electrode zone, an electrolyte in the intermediate transition zone, and an electrolyte in the far-electrode zone. The electrolyte in the near-electrode zone, the electrolyte in the intermediate transition zone, and the electrolyte in the far-electrode zone are dynamically supplied in a volume ratio of 1:0.5:0.2. The electrolyte in the near-electrode zone includes 0.6 mol / L Zr(NO3)4 and 0.1 mol / L Y(NO3)3, the electrolyte in the intermediate transition zone includes 0.3 mol / L Zr(NO3)4 and 0.05 mol / L Y(NO3)3, and the electrolyte in the far-electrode zone includes 0.1 mol / L Zr(NO3)4 and 0.02 mol / L Y(NO3)3.

[0063] When the surface of the stranded aluminum conductor is subjected to pulse-modulated plasma electrolytic oxidation treatment in a gradient concentration electrolyte system, a three-stage discharge parameter control is adopted to sequentially form the transition layer, protective layer and functional layer in the gradient composite film. In the transition layer formation stage, the discharge voltage is 350 V, the discharge frequency is 150 Hz, the discharge duty cycle is 40%, and the discharge duration is 300 s; in the protective layer growth stage, the discharge voltage is 400 V, the discharge frequency is 200 Hz, the discharge duty cycle is 50%, and the discharge duration is 480 s; in the functional layer regulation stage, the discharge voltage is 300 V, the discharge frequency is 100 Hz, the discharge duty cycle is 30%, and the discharge duration is 180 s.

[0064] After constructing a gradient composite film on the surface of the twisted aluminum conductor, the aluminum conductor with the gradient composite film was heated to 80°C at a heating rate of 2°C / min in a vacuum environment. After being kept warm for 20 minutes, the temperature was increased to 125°C at a heating rate of 5°C / min and kept warm for 35 minutes.

[0065] Example 5

[0066] Before constructing the gradient composite film on the surface of the stranded aluminum conductor, the surface of the stranded aluminum conductor was sandblasted with α-Al2O3 abrasive with a particle size of 90 μm and a sandblasting pressure of 0.5 MPa. After sandblasting, the surface roughness Ra of the stranded aluminum conductor was 4 μm.

[0067] A gradient concentration electrolyte system is constructed by dynamically supplying electrolytes of different components in different zones. The gradient concentration electrolyte system consists of an electrolyte in the near-electrode zone, an electrolyte in the intermediate transition zone, and an electrolyte in the far-electrode zone. The electrolyte in the near-electrode zone, the electrolyte in the intermediate transition zone, and the electrolyte in the far-electrode zone are dynamically supplied in a volume ratio of 1:0.5:0.2. The electrolyte in the near-electrode zone includes 0.4 mol / L Zr(NO3)4 and 0.07 mol / L Y(NO3)3, the electrolyte in the intermediate transition zone includes 0.15 mol / L Zr(NO3)4 and 0.03 mol / L Y(NO3)3, and the electrolyte in the far-electrode zone includes 0.06 mol / L Zr(NO3)4 and 0.012 mol / L Y(NO3)3.

[0068] When the surface of the stranded aluminum conductor is subjected to pulse-modulated plasma electrolytic oxidation treatment in a gradient concentration electrolyte system, a three-stage discharge parameter control is adopted to sequentially form the transition layer, protective layer and functional layer in the gradient composite film. In the transition layer formation stage, the discharge voltage is 300 V, the discharge frequency is 130 Hz, the discharge duty cycle is 38%, and the discharge duration is 270 s; in the protective layer growth stage, the discharge voltage is 370 V, the discharge frequency is 170 Hz, the discharge duty cycle is 43%, and the discharge duration is 420 s; in the functional layer regulation stage, the discharge voltage is 270 V, the discharge frequency is 70 Hz, the discharge duty cycle is 22%, and the discharge duration is 132 s.

[0069] After constructing a gradient composite film on the surface of the twisted aluminum conductor, the aluminum conductor with the gradient composite film was heated to 80°C at a heating rate of 2°C / min in a vacuum environment. After being kept warm for 20 minutes, the temperature was increased to 125°C at a heating rate of 5°C / min and kept warm for 35 minutes.

[0070] Example 6

[0071] Before constructing the gradient composite film on the surface of the stranded aluminum conductor, the surface of the stranded aluminum conductor was sandblasted with α-Al2O3 abrasive with a particle size of 110 μm and a sandblasting pressure of 0.7 MPa. After sandblasting, the surface roughness Ra of the stranded aluminum conductor was 5.5 μm.

[0072] A gradient concentration electrolyte system is constructed by dynamically supplying electrolytes of different components in different zones. The gradient concentration electrolyte system consists of an electrolyte in the near-electrode zone, an electrolyte in the intermediate transition zone, and an electrolyte in the far-electrode zone. The electrolyte in the near-electrode zone, the electrolyte in the intermediate transition zone, and the electrolyte in the far-electrode zone are dynamically supplied in a volume ratio of 1:0.5:0.2. The electrolyte in the near-electrode zone includes 0.5 mol / L Zr(NO3)4 and 0.09 mol / L Y(NO3)3, the electrolyte in the intermediate transition zone includes 0.25 mol / L Zr(NO3)4 and 0.045 mol / L Y(NO3)3, and the electrolyte in the far-electrode zone includes 0.09 mol / L Zr(NO3)4 and 0.018 mol / L Y(NO3)3.

[0073] When the surface of the stranded aluminum conductor is subjected to pulse-modulated plasma electrolytic oxidation treatment in a gradient concentration electrolyte system, a three-stage discharge parameter control is adopted to sequentially form the transition layer, protective layer and functional layer in the gradient composite film. In the transition layer formation stage, the discharge voltage is 340V, the discharge frequency is 140Hz, the discharge duty cycle is 37%, and the discharge duration is 288s; in the protective layer growth stage, the discharge voltage is 390V, the discharge frequency is 190Hz, the discharge duty cycle is 48%, and the discharge duration is 450s; in the functional layer regulation stage, the discharge voltage is 290V, the discharge frequency is 90Hz, the discharge duty cycle is 28%, and the discharge duration is 168s.

[0074] After constructing a gradient composite film on the surface of the twisted aluminum conductor, the aluminum conductor with the gradient composite film was heated to 80°C at a heating rate of 2°C / min in a vacuum environment. After being kept warm for 20 minutes, the temperature was increased to 125°C at a heating rate of 5°C / min and kept warm for 35 minutes.

[0075] Example 7

[0076] The gradient composite films prepared in Examples 2 to 6 were measured for film thickness and analyzed for composition using a Hitachi SU8020 cold field emission scanning electron microscope equipped with an EDS detector. When preparing the test samples, wire samples of 10 mm in length were cut, inlaid with epoxy resin, and then polished in cross section, and subjected to a 5 nm gold spraying treatment. The test acceleration voltage was 15 kV, and the test working distance was 10 mm. The film structure thickness parameters of the gradient composite films prepared in Examples 2 to 6 are shown in Table 1. The EDS composition analysis results of the gradient composite films prepared in Examples 2 to 6 are shown in Table 2. Figure 2 This is a SEM image of the gradient composite membrane prepared according to Example 2 of the present invention.

[0077] Table 1

[0078] Example Transition layer thickness μm Protective layer thickness μm Functional layer thickness μm Example 2 3.2±0.3 20.5±0.9 5.1±0.6 Example 3 2.1±0.2 15.8±0.6 3.3±0.2 Example 4 5.2±0.4 25.2±1.1 8.0±0.4 Example 5 4.0±0.2 18.5±0.5 6.2±0.3 Example 6 3.5±0.3 22.3±0.8 7.3±0.3

[0079] As shown in Table 1, the gradient composite film for the corrosion-resistant overhead conductor prepared in the embodiment of the present invention has a transition layer thickness of 2.1-5.2 μm, a protective layer thickness of 15.8-25.2 μm, and a functional layer thickness of 3.3-8.0 μm.

[0080] Table 2

[0081]

[0082]

[0083] The gradient composite films prepared in Examples 2 to 6 were subjected to XRD phase detection using a PANalytical X-Pert PRO MPD X-ray diffractometer from the Netherlands. The main XRD phase diffraction peaks of the gradient composite films prepared in Examples 2 to 6 of the present invention are listed in Table 3. Figure 3 XRD phase quantitative diagrams of the gradient composite films prepared according to Examples 2 to 6 of the present invention, Figure 4 is the XRD phase grain size diagram of the gradient composite film prepared according to Examples 2 to 6 of the present invention, Figure 5 2 are XRD phase distribution diagrams of the gradient composite films prepared according to Examples 2 to 6 of the present invention.

[0084] Table 3

[0085]

[0086]

[0087]

[0088] From Table 2, Table 3, Figure 3 、 Figure 4 and Figure 5 As can be seen, the gradient composite membrane prepared in this embodiment of the present invention comprises, from the inside out, a transition layer, a protective layer, and a functional layer. The transition layer primarily consists of an amorphous phase and an α-Al2O3 phase, with the Zr content decreasing gradually from 100 at% to 30-35 at%. The synergistic effect of the amorphous and Al2O3 phases enhances the bonding strength and toughness of the transition layer, providing a good foundation for the protective layer while also providing some antioxidant properties.

[0089] The protective layer is composed of t-ZrO2, m-ZrO2, and Y2O3 phases, with the Y2O3 content decreasing gradually from 8-9 mol% to 2-4 mol% from the inside out. The combined effects of the t-ZrO2 and m-ZrO2 phases provide excellent wear and corrosion resistance, while the Y2O3 phase stabilizes the ZrO2 structure, further enhancing the performance of the protective layer.

[0090] The functional layer is mainly composed of t-ZrO2 phase and m-ZrO2 phase, and the ratio of the two is between 1.2-2.6:1. The change in the ratio of t-ZrO2 phase and m-ZrO2 phase optimizes the surface wear resistance and oxidation resistance, enables the functional layer to effectively resist the erosion of the external environment, and optimizes the overall performance of the composite membrane.

[0091] On the other hand, in the gradient composite film prepared by the present invention, the α-Al2O3 phase content is between 15% and 24%, with a grain size between 30 and 38 nm; the t-ZrO2 phase content is between 20% and 36%, with a grain size between 22 and 28 nm; the m-ZrO2 phase content is between 11% and 28%, with a grain size between 18 and 24 nm; the Y2O3 phase content is between 6% and 16%, with a grain size between 15 and 19 nm. The Y2O3 phase content gradually decreases in the protective layer, and the grain size changes slightly, indicating that the Y2O3 phase plays a role in stabilizing the structure of the protective layer.

[0092] In the embodiments of the present invention, the surface roughness of the sandblasting treatment has a significant effect on the content and grain size of the phases. As the surface roughness increases, the content and grain size of each phase increase. This is because the sandblasting treatment increases the active sites on the surface and promotes the growth of the phases. Changes in the composition of the electrolyte and the processing parameters in different embodiments also affect the formation and distribution of the phases. For example, higher Zr(NO3)4 and Y(NO3)3 concentrations promote the formation of t-ZrO2 phase and Y2O3 phase, while lower concentrations promote the formation of m-ZrO2 phase.

[0093] A neutral salt spray corrosion test was conducted on the conductors prepared in Examples 2 to 6 of the present invention using a Q-Fog CCT1100 salt spray corrosion chamber. Three parallel samples were taken for each example. The sample specification was ACSR240 (a steel core aluminum stranded wire with a specification of 240). The sample was ultrasonically cleaned with anhydrous ethanol before the test. After drying, the non-test area was protected with insulating tape. The test solution was a 5% NaCl solution, the test temperature was 35±1°C, and the spray pressure was continuously sprayed at 0.8-1.2 bar for 500 hours. A control group was set up in the test. The control group used ordinary steel core aluminum stranded wire (without gradient composite film). The initial weight and the final weight were recorded, and the corrosion weight loss and the corrosion area ratio (average value of the three samples) were calculated. See Table 4 below. Figure 6 The figure is a corrosion rate diagram calculated based on the corrosion weight loss of inventive examples 2 to 6 and the control group.

[0094] Table 4

[0095] Example Initial mass g Termination mass g Corrosion weight loss g Corrosion area percentage Example 2 1050.50 1050.38 0.12 2.5 Example 3 1051.80 1051.65 0.15 3 Example 4 1049.20 1049.10 0.10 2 Example 5 1052.60 1052.47 0.13 2.7 Example 6 1050.90 1050.79 0.11 2.3 control group 1051.30 1049.80 1.50 25

[0096] As shown in Table 4, the corrosion weight loss range of the corrosion-resistant overhead wires prepared in Examples 2 to 6 of the present invention is 0.10-0.15g, which is significantly lower than 1.50g of the control group (reduced by about 90%). Among them, the corrosion-resistant overhead wire of Example 4 performs the best. The corrosion area of ​​the corrosion-resistant overhead wires prepared in Examples 2 to 6 of the present invention is no more than 3%, which is significantly lower than the corrosion area ratio of the control group. The corrosion rate of the corrosion-resistant overhead wires prepared in Examples 2 to 6 of the present invention is ≤0.010g / (m 2 ·h), only the control group (0.100g / (m 2 ·h)) is 1 / 10 of that of the conventional air compressor, and its service life is increased by 10 times.

[0097] The morphology of the samples of Example 3, Example 4 and the control group (after the salt spray corrosion test) was observed using a Hitachi SU8020 cold field emission scanning electron microscope. Figure 7 This is a SEM morphology of the corrosion-resistant overhead wire prepared according to Example 3 of the invention after 500 hours of salt spray test. Figure 8 This is a SEM morphology of the corrosion-resistant overhead wire prepared according to Example 4 of the invention after 500 hours of salt spray test. Figure 9 The SEM morphology of the overhead wire prepared according to the control group after 500h salt spray test. Figure 7 、 Figure 8 and Figure 9 As shown in the figure, after 500 hours of salt spray corrosion test, the corrosion-resistant overhead wire prepared in the embodiment of the present invention has no obvious salt spray corrosion damage on the surface due to the stable gradient composite film, while the surface of the overhead wire in the control group is largely covered by white corrosion products and suffers from severe local corrosion.

[0098] In this embodiment of the present invention, a transition layer with a decreasing Zr content provides a stable base for the protective layer. The aluminum conductor surface is optimized through sandblasting, enhancing film adhesion and reducing penetration of corrosive media. The Y2O3 phase content in the protective layer is reduced, stabilizing the ZrO2 phase structure and suppressing phase transformation cracking. Regulating the phase ratio of the functional layer further optimizes resistance to environmental corrosion.

[0099] In practical applications, this embodiment utilizes electrolyte gradient control to promote the formation of a dense transition layer, ensuring a continuous gradient of composition. Voltage is regulated in stages to match the growth requirements of each layer, avoiding film defects caused by internal stress concentration. Vacuum step curing eliminates microcracks in the film, improving overall long-term corrosion resistance.

[0100] The corrosion-resistant overhead conductor prepared by the present invention has excellent corrosion resistance, and the gradient composite film can serve in harsh environments such as coastal salt spray and industrial acid rain.

[0101] The adhesion of the gradient composite films prepared in Examples 2 to 6 was tested according to "ASTM D4541-17 Standard Test Method for Pull-off Strength of Coatings Using a Portable Adhesion Tester". The testing equipment includes: Instron 5967 tensile testing machine, PosiTest AT-A adhesion tester. 20 specimens (length 100 mm) were cut from each of Examples 2-6, keeping the gradient composite film intact, the test area was lightly polished with sandpaper, cleaned with alcohol and dried, and the aluminum pulling head was bonded to the test area using AB glue and cured at 25°C for 24 hours. The specimen was fixed on the tensile testing machine with a vertical pulling speed of 1.0 mm / min. The maximum tensile force when the film layer was peeled off was recorded and converted into adhesion. The adhesion test results are shown in Table 5 below.

[0102] Table 5

[0103] Example Adhesion MPa Failure mode ratio A / B Example 2 28.5 A (85%), B (15%) Example 3 25.3 A (80%), B (20%) Example 4 30.1 A (90%), B (10%) Example 5 27.8 A (80%), B (20%) Example 6 29.4 A (85%), B (15%)

[0104] In Table 5, A indicates internal fracture of the gradient composite film, a failure mode that represents ideal bonding, where the bond strength between the surface gradient composite film and the substrate is greater than the strength of the gradient composite film itself. B indicates delamination of the gradient composite film from the substrate interface. For the corrosion-resistant overhead conductors prepared in Examples 2-6 of the present invention, the gradient composite film exhibited adhesion of no less than 25.3 MPa on the aluminum conductor surface, with 80% failure mode A, indicating a strong bond between the gradient composite film and the aluminum conductor substrate.

[0105] In practical applications, the corrosion-resistant overhead conductor and the manufacturing method thereof according to the embodiments of the present invention have the following beneficial technical effects:

[0106] 1. By constructing a gradient concentration electrolyte system and in-situ growth, a gradient composite membrane with continuous gradient changes in composition and structure is constructed, which includes a transition layer, a protective layer and a functional layer from the inside to the outside.

[0107] 2. The gradient composite film significantly improves the corrosion resistance of the aluminum conductor surface, allowing the corrosion-resistant overhead wires to operate stably for a long time in complex corrosive environments such as coastal salt spray and industrial acid rain, effectively solving the problem of existing overhead wires being prone to corrosion and failure in harsh environments.

[0108] 3. The high-strength combination of the gradient composite film and the aluminum conductor matrix ensures that the gradient composite film will not peel off or fail due to external factors during long-term use, further protecting the corrosion resistance of the conductor.

[0109] 4. Pulsed plasma electrolytic oxidation treatment is used, and a gradient concentration electrolyte system is established by dynamically supplying different electrolyte components in different zones, enabling the in-situ construction of a gradient composite membrane. This method offers advantages such as simplicity, ease of operation, and low cost. It is also suitable for industrial continuous production and readily applicable, meeting the needs of large-scale production of corrosion-resistant overhead conductors.

[0110] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A corrosion-resistant overhead conductor comprising a load-bearing member and a stranded aluminum conductor disposed outside the load-bearing member, characterized in that: The outermost layer of the stranded aluminum conductor has a gradient composite film with continuously changing composition and structure. The gradient composite film includes, from the inside to the outside, a transition layer, a protective layer, and a functional layer. The transition layer is composed of an amorphous phase and an α-Al2O3 phase, the protective layer is composed of a t-ZrO2 phase, an m-ZrO2 phase, and a Y2O3 phase, and the surface functional layer is composed of a t-ZrO2 phase and an m-ZrO2 phase.

2. The corrosion-resistant overhead conductor according to claim 1, characterized in that: The Zr element content of the transition layer decreases from 100at% to 30-35at% from the inside to the outside, and the Y2O3 phase content of the protective layer decreases from 8-9mol% to 2-4mol% from the inside to the outside. The ratio of t-ZrO2 phase and m-ZrO2 phase in the surface functional layer is 1.2-2.6:

1.

3. A method for preparing a corrosion-resistant overhead conductor, characterized in that: The method comprises: constructing a gradient concentration electrolyte system, and in-situ constructing a gradient composite film with continuously changing composition and structure on the surface of a stranded aluminum conductor through pulse modulation plasma electrolytic oxidation treatment in the gradient concentration electrolyte system.

4. The method for preparing a corrosion-resistant overhead conductor according to claim 3, wherein: A gradient concentration electrolyte system is constructed by dynamically supplying electrolytes of different components in different zones. The gradient concentration electrolyte system consists of an electrolyte in the near-electrode area, an electrolyte in the intermediate transition area, and an electrolyte in the far-electrode area. The electrolyte in the near-electrode area, the electrolyte in the intermediate transition area, and the electrolyte in the far-electrode area are dynamically supplied in a volume ratio of 1:0.5:0.

2.

5. The method for preparing a corrosion-resistant overhead conductor according to claim 4, characterized in that: The electrolyte in the near-electrode area includes 0.3-0.6 mol / L Zr(NO3)4 and 0.05-0.1 mol / L Y(NO3)3, the electrolyte in the intermediate transition area includes 0.1-0.3 mol / L Zr(NO3)4 and 0.02-0.05 mol / L Y(NO3)3, and the electrolyte in the far-electrode area includes 0.05-0.1 mol / L Zr(NO3)4 and 0.01-0.02 mol / L Y(NO3)3.

6. The method for preparing a corrosion-resistant overhead conductor according to claim 3, wherein: When the surface of a stranded aluminum conductor is subjected to pulse-modulated plasma electrolytic oxidation treatment in a gradient concentration electrolyte system, a transition layer, a protective layer and a functional layer in the gradient composite film are sequentially formed by controlling three-stage discharge parameters.

7. The method for preparing a corrosion-resistant overhead conductor according to claim 6, wherein: The transition layer, protective layer and functional layer in the gradient composite film are formed in sequence by controlling the three-stage discharge parameters, including: During the transition layer formation stage, the discharge voltage is 300-350V, the discharge frequency is 100-150Hz, the discharge duty cycle is 30-40%, and the discharge duration is 180-300s; During the protective layer growth stage, the discharge voltage is 350-400V, the discharge frequency is 150-200Hz, the discharge duty cycle is 40-50%, and the discharge duration is 300-480s; During the functional layer regulation stage, the discharge voltage is 250-300V, the discharge frequency is 50-100Hz, the discharge duty cycle is 20-30%, and the discharge duration is 120-180s.

8. The method for preparing a corrosion-resistant overhead conductor according to claim 3, wherein: Before constructing the gradient composite film on the surface of the stranded aluminum conductor, the surface of the stranded aluminum conductor is sandblasted with α-Al2O3 abrasive with a particle size of 80-120 μm. The sandblasting pressure is 0.4-0.8 MPa. After sandblasting, the surface roughness Ra of the stranded aluminum conductor is 3.2-6.4 μm.

9. The method for preparing a corrosion-resistant overhead conductor according to claim 3, wherein: After a gradient composite film is constructed on the surface of a twisted aluminum conductor, the aluminum conductor with the gradient composite film on the surface is subjected to a step curing process in a vacuum environment.

10. The method for preparing a corrosion-resistant overhead conductor according to claim 9, wherein: In a vacuum environment, the aluminum wire with the gradient composite film was heated to 80°C at a heating rate of 2°C / min, kept warm for 20 minutes, and then heated to 125°C at a heating rate of 5°C / min and kept warm for 35 minutes.

Images