Aluminum clad mild steel wire with high interfacial bonding strength and preparation method thereof
By introducing a zinc alloy transition layer and a composite anti-corrosion layer into aluminum-clad Invar strands, the problem of insufficient interfacial bonding strength is solved, achieving a synergistic improvement in high mechanical strength, low thermal expansion coefficient, and excellent conductivity, making it suitable for high-temperature transmission conductors and capacity-upgrading conductors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 江苏冠晟超导科技有限公司
- Filing Date
- 2026-03-31
- Publication Date
- 2026-06-05
Smart Images
Figure CN122158229A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of metal composite conductor materials, specifically relating to an aluminum-clad Invar stranded wire with high interfacial bonding strength and its preparation method. Background Technology
[0002] As transmission lines develop towards longer spans, larger capacities, higher temperature resistance, and lower sag, traditional steel-cored aluminum stranded wires can no longer simultaneously meet the comprehensive requirements of high mechanical strength, low coefficient of thermal expansion, excellent conductivity, and long-term service reliability. Invar steel, due to its low coefficient of thermal expansion and good mechanical properties, is considered one of the preferred materials for low-sag conductor cores. Coating an aluminum layer around an Invar core to create aluminum-clad Invar single wires, and further stranding them to form aluminum-clad Invar stranded wires, can balance the low thermal expansion characteristics of the Invar core with the conductivity of the aluminum layer, showing promising application prospects in high-temperature transmission conductors and capacity-upgrading conductors.
[0003] However, existing aluminum-clad Invar stranded wires still have some shortcomings. First, Invar and aluminum belong to different metal systems, with significant differences in thermophysical properties, surface conditions, and interfacial diffusion behavior. Direct bonding can easily lead to the formation of oxide layers, micropores, or stress concentration zones at the interface, resulting in insufficient interfacial bonding strength. This, in turn, can cause delamination and peeling during subsequent drawing, stranding, bending, or long-term thermal cycling. Second, while some existing technologies improve interfacial bonding through surface cleaning, hot-dip galvanizing, or mechanical bonding, they primarily focus on strengthening a single interface, neglecting the synergistic consideration between interfacial bonding and subsequent corrosion protection. Especially in humid, high-salt-spray, or industrial corrosive environments, the outer aluminum layer of the conductor is prone to corrosion damage, thus affecting overall conductivity and service life. Summary of the Invention
[0004] To address the shortcomings mentioned in the background art, the present invention aims to provide an aluminum-clad Invar strand with high interfacial bonding strength and its preparation method. By setting a zinc alloy transition layer containing zinc, aluminum and trace rare earth elements between the Invar core and the aluminum layer, and constructing a composite anti-corrosion layer composed of an anodic oxide layer and a graphene reinforcement layer on the outer surface of the aluminum layer, the interfacial bonding strength, corrosion resistance and long-term service stability of the aluminum-Invar are improved.
[0005] The objective of this invention can be achieved through the following technical solutions: A high interface bonding strength aluminum-clad Invar stranded wire, the aluminum-clad Invar stranded wire includes a stranded structure formed by stranding several aluminum-clad Invar single wires, and the aluminum-clad Invar single wire includes, from the inside to the outside, an Invar core, a zinc alloy transition layer, an aluminum layer and a composite anti-corrosion layer. The Invar steel core is made from the following raw materials, by weight: 33.5-35.5 parts nickel, 0.5-0.7 parts chromium, 0.6-0.9 parts cobalt, 1.0-1.15 parts molybdenum, and other impurity elements totaling no more than 0.10 parts, with the balance being iron. The zinc alloy transition layer is made of the following raw materials, by mass: 78-85 parts zinc, 12-19 parts aluminum, 0.3-0.8 parts trace rare earth elements, and unavoidable impurities, the total amount of which is no more than 1.2 parts; The aluminum layer is 1060 industrial pure aluminum, made from the following raw materials, by mass: no more than 0.25 parts silicon, no more than 0.35 parts iron, no more than 0.05 parts copper, no more than 0.10 parts other impurities, and the balance is aluminum; The composite anti-corrosion layer consists of an inner anodic oxide layer and an outer graphene reinforcement layer.
[0006] More preferably, the trace rare earth element in the zinc alloy transition layer is a mixture of cerium and lanthanum, and the mass ratio of cerium to lanthanum is 1.8 to 2.2:1, and the amount of cerium is 0.2 to 0.53 parts, and the amount of lanthanum is 0.1 to 0.27 parts.
[0007] More preferably, the thickness of the zinc alloy transition layer is 0.18–0.50 mm.
[0008] More preferably, in the composite anti-corrosion layer, the thickness of the anodic oxide layer is 0.12-0.20 mm, the thickness of the graphene reinforcement layer is 0.06-0.10 mm, and the ratio of the thickness of the zinc alloy transition layer to the thickness of the anodic oxide layer is 1.5-2.5:1.
[0009] More preferably, the graphene in the graphene reinforcement layer is obtained by reducing graphene oxide, and the purity of the graphene is not less than 99.5%.
[0010] A method for preparing aluminum-clad Invar strand with high interfacial bonding strength includes the following steps: S1. Weigh each raw material, and carry out smelting, casting, hot working, cold drawing and heat treatment to obtain Invar steel core; S2. After pretreatment of the Invar core, a zinc alloy transition layer is formed on the surface of the Invar core using a hot-dip galvanizing process; S3. An aluminum layer is coated onto the outside of the zinc alloy transition layer using a continuous extrusion coating process to obtain an aluminum-clad Invar single wire; S4. The aluminum layer surface of the aluminum-clad Invar single wire is first subjected to micro-arc oxidation treatment to form an anodic oxide layer, and then graphene coating and reduction treatment are performed to form a graphene reinforcement layer, thereby obtaining an aluminum-clad Invar single wire with a composite anti-corrosion layer. S5. Twist multiple aluminum-clad Invar single wires together to obtain the aluminum-clad Invar stranded wire with high interfacial bonding strength.
[0011] More preferably, in step S2, the pretreatment includes pickling, cleaning and preheating; the zinc alloy melt used in the hot-dip galvanizing process is obtained by smelting the following raw materials: 78-85 parts zinc, 12-19 parts aluminum, 0.3-0.8 parts trace rare earth elements, and unavoidable impurities, and is degassed after smelting.
[0012] More preferably, in step S3, after continuous extrusion coating is completed, the obtained aluminum-clad Invar single wire is subjected to low-temperature aging treatment; in step S5, the stranding adopts concentric stranding combined with untwisting treatment, and after stranding is completed, low-temperature curing treatment is performed.
[0013] More preferably, in step S4, the micro-arc oxidation treatment adopts a constant current mode, and the micro-arc oxidation electrolyte is doped with α-Al2O3 nanoparticles; the graphene coating and reduction treatment includes: preparing a graphene oxide dispersion, coating it on the surface of the anodic oxide layer, and performing a reduction treatment after drying to form a graphene reinforcement layer.
[0014] More preferably, the graphene oxide dispersion is prepared by the following method: adding graphene oxide to deionized water, then adding a dispersant, and dispersing by ultrasonication to obtain a uniform dispersion.
[0015] The beneficial effects of this invention are: This invention introduces a zinc alloy transition layer containing zinc, aluminum, and trace rare earth elements between the Invar core and the aluminum layer. This transition layer not only possesses good compositional compatibility with the outer aluminum layer but also improves the interfacial wetting and atomic diffusion conditions between the Invar matrix and the aluminum layer. Zinc reduces the difficulty of interfacial bonding, aluminum helps enhance the continuity of the bond with the outer aluminum layer, and rare earth elements refine the grains, purify the interface, reduce local stress concentration, and inhibit the formation of an interfacial oxide film. This significantly improves the bonding strength of the aluminum-Invar interface and reduces the risk of delamination and peeling during subsequent drawing, stranding, and service. Simultaneously, this invention constructs a composite anti-corrosion layer on the outer surface of the aluminum layer, consisting of an anodic oxide layer and a graphene reinforcement layer. The anodic oxide layer forms a dense and stable oxide protective barrier, while the graphene reinforcement layer further fills the micropores and microcracks in the anodic oxide layer, extending the penetration path of corrosive media and improving the surface barrier and corrosion resistance. Furthermore, the low-temperature construction method avoids thermal damage to the inner aluminum-Invar composite interface, achieving a synergistic unity of interface strengthening and outer layer protection. Attached Figure Description
[0016] The invention will now be further described with reference to the accompanying drawings.
[0017] Figure 1This is a comparison chart of the interface strength and retention rate of the example and comparative samples after 50 thermal cycles. Detailed Implementation
[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0019] Example 1: Verification of the feasibility of the present invention and the synergistic effect of interface enhancement and corrosion prevention under conditions of lower component ratio and thinner layer structure.
[0020] S1. Take 3.35 kg of nickel, 0.05 kg of chromium, 0.06 kg of cobalt, 0.10 kg of molybdenum, with the balance being iron, and control the total amount of other impurity elements to within 0.01 kg. Melt the above raw materials under an argon protective atmosphere and cast them into ingots. After hot working, cold drawing and heat treatment, an Invar steel core with a diameter of 2.50 mm is obtained.
[0021] S2. Weigh 7.80 kg of zinc, 1.20 kg of aluminum, and 0.03 kg of trace rare earth elements, wherein the trace rare earth elements are cerium and lanthanum, with a mass ratio of cerium to lanthanum of 1.8:1. Melt and degas the components to obtain a zinc alloy melt. After pickling, cleaning, and preheating, the Invar core obtained in step S1 is subjected to a hot-dip galvanizing process to form a zinc alloy transition layer on its surface. The hot-dip galvanizing temperature is controlled at 455℃, and the thickness of the resulting zinc alloy transition layer is 0.18 mm.
[0022] S3. 1060 industrial pure aluminum is selected as the cladding material. A continuous extrusion cladding process is adopted to clad the 1060 industrial pure aluminum on the outside of the zinc alloy transition layer. The cladding temperature is controlled at 420-450℃. After cladding, a low-temperature aging treatment is performed to obtain aluminum-clad Invar single wire.
[0023] S4. The aluminum-clad Invar single wire obtained in step S3 is subjected to micro-arc oxidation treatment to form an anodic oxide layer with a thickness of 0.12 mm on the outer surface of the aluminum layer. The micro-arc oxidation treatment adopts a constant current mode, and the electrolyte contains α-Al2O3 nanoparticles. Subsequently, a graphene oxide dispersion is coated on the surface of the anodic oxide layer, and after drying and reduction treatment, a graphene reinforcement layer with a thickness of 0.06 mm is formed. The purity of the graphene is not less than 99.5%, thereby obtaining a composite anti-corrosion layer.
[0024] S5. The aluminum-clad Invar single wires obtained in step S4 are concentrically stranded and combined with untwisting treatment. After stranding, a low-temperature curing treatment is performed to obtain aluminum-clad Invar stranded wires with high interfacial bonding strength.
[0025] Example 2: Verification of the feasibility of the present invention and the synergistic effect of interface enhancement and corrosion prevention under conditions of higher component ratio and thicker layer structure.
[0026] S1. Take 3.55 kg of nickel, 0.07 kg of chromium, 0.09 kg of cobalt, 0.115 kg of molybdenum, and approximately 6.165 kg of iron, with the total amount of other impurity elements controlled within 0.01 kg. Melt the above raw materials under an argon protective atmosphere and cast them into ingots. After hot working, cold drawing, and heat treatment, an Invar steel core with a diameter of 2.50 mm is obtained.
[0027] S2. Take 8.50 kg of zinc, 1.90 kg of aluminum, and 0.08 kg of trace rare earth elements, wherein the trace rare earth elements are cerium and lanthanum, with a mass ratio of cerium to lanthanum of 2.2:1, corresponding to approximately 0.055 kg of cerium and approximately 0.025 kg of lanthanum. Add zinc, aluminum, and trace rare earth elements to a smelting apparatus and smelt uniformly at 450–470°C, followed by degassing to obtain a zinc alloy melt. After sequentially pickling, cleaning, and preheating treatment, the Invar core obtained in step S1 is subjected to a hot-dip galvanizing process to form a zinc alloy transition layer on its surface. The hot-dip galvanizing temperature is controlled at 460°C. After galvanizing, a sizing treatment is performed to make the zinc alloy transition layer thickness 0.50 mm.
[0028] S3. Using 1060 industrial pure aluminum as the cladding material, a continuous extrusion cladding process is employed to coat the outside of the zinc alloy transition layer with 1060 industrial pure aluminum. The cladding temperature is controlled at 430–450°C, resulting in an aluminum-clad Invar single wire with an outer aluminum coating. After continuous extrusion cladding, the resulting single wire undergoes a low-temperature aging treatment.
[0029] S4. The aluminum-clad Invar single wire obtained in step S3 is subjected to micro-arc oxidation treatment to form an anodic oxide layer on the outer surface of the aluminum layer. The micro-arc oxidation treatment adopts a constant current mode, and the electrolyte contains α-Al2O3 nanoparticles. The thickness of the resulting anodic oxide layer is 0.20 mm. Subsequently, a graphene oxide dispersion is prepared and coated on the surface of the anodic oxide layer. After drying and reduction treatment, a graphene reinforcement layer is formed with a thickness of 0.10 mm and a graphene purity of not less than 99.5%, thereby forming a composite anti-corrosion layer on the outside of the aluminum layer. At this time, the ratio of the zinc alloy transition layer thickness to the anodic oxide layer thickness is 2.5:1.
[0030] S5. The aluminum-clad Invar single wires obtained in step S4 are concentrically stranded and combined with untwisting treatment. After stranding, a low-temperature curing treatment is performed to obtain the aluminum-clad Invar stranded wire with high interfacial bonding strength.
[0031] Example 3: Verification of the feasibility of the present invention and the synergistic effect of interface enhancement and corrosion prevention under moderate component ratio and structural conditions.
[0032] S1. Take 3.45 kg of nickel, 0.06 kg of chromium, 0.075 kg of cobalt, 0.1075 kg of molybdenum, and approximately 6.2975 kg of iron, with the total amount of other impurity elements controlled to within 0.01 kg. Melt the above raw materials under an argon protective atmosphere, and after melting, cast them into ingots; the resulting ingots are hot-worked to form wire blanks, and then cold-drawn and heat-treated to obtain Invar steel cores with a diameter of 2.50 mm.
[0033] S2. Take 8.15 kg of zinc, 1.55 kg of aluminum, and 0.055 kg of trace rare earth elements, wherein the trace rare earth elements are cerium and lanthanum, with a mass ratio of cerium to lanthanum of 2.0:1, corresponding to approximately 0.0367 kg of cerium and approximately 0.0183 kg of lanthanum. Melt the zinc, aluminum, and trace rare earth elements uniformly in a smelting apparatus at 450–470°C, and then perform degassing treatment to obtain a zinc alloy melt. After pickling, cleaning, and preheating treatment, the Invar core obtained in step S1 is subjected to a hot-dip galvanizing process to form a zinc alloy transition layer on its surface. The hot-dip galvanizing temperature is controlled at 455–460°C, and the thickness of the resulting zinc alloy transition layer is 0.34 mm.
[0034] S3. Using 1060 industrial pure aluminum as the cladding material, a continuous extrusion cladding process is employed to clad the 1060 industrial pure aluminum onto the outside of the zinc alloy transition layer. The cladding temperature is controlled at 420–450°C, resulting in an aluminum-clad Invar single wire with an outer aluminum coating. After continuous extrusion cladding, the resulting aluminum-clad Invar single wire is placed in a blast furnace and held at 180°C for 2 hours. It is then removed and air-cooled to room temperature to complete the low-temperature aging treatment.
[0035] S4. The aluminum-clad Invar single wire obtained in step S3 is subjected to micro-arc oxidation treatment to form an anodic oxide layer on the outer surface of the aluminum layer. The micro-arc oxidation treatment adopts a constant current mode, and the electrolyte contains α-Al2O3 nanoparticles. The thickness of the resulting anodic oxide layer is 0.16 mm. Subsequently, a graphene oxide dispersion is prepared and coated on the surface of the anodic oxide layer. After drying and reduction treatment, a graphene reinforcement layer is formed with a thickness of 0.08 mm and a graphene purity of not less than 99.5%, thereby forming a composite anti-corrosion layer on the outside of the aluminum layer. At this time, the ratio of the zinc alloy transition layer thickness to the anodic oxide layer thickness is approximately 2.1:1.
[0036] S5. The aluminum-clad Invar single wires obtained in step S4 are concentrically stranded and combined with untwisting treatment. After stranding, a low-temperature curing treatment is performed to obtain the aluminum-clad Invar stranded wire with high interfacial bonding strength.
[0037] Comparative Example 1: Preparation and performance of aluminum layer directly composited with Invar core without zinc alloy transition layer.
[0038] S1. Take 3.45 kg of nickel, 0.06 kg of chromium, 0.075 kg of cobalt, 0.1075 kg of molybdenum, with the balance being iron, and control the total amount of other impurity elements to within 0.01 kg. Melt the above raw materials under an argon protective atmosphere, and after melting, cast them into ingots; the resulting ingots are hot-worked to form wire blanks, and then cold-drawn and heat-treated to obtain Invar steel cores with a diameter of 2.50 mm.
[0039] S2. The Invar core obtained in step S1 is subjected to pickling, cleaning, and preheating treatment. The pickling uses an 8% hydrochloric acid solution, followed by rinsing with deionized water. The preheating temperature is controlled at 180℃ to remove surface oxides and impurities, improving the quality of subsequent coating. Hot-dip galvanizing is not performed to avoid forming a zinc alloy transition layer on the surface of the Invar core.
[0040] S3. 1060 industrial pure aluminum is selected as the cladding material. A continuous extrusion cladding process is used to directly clad the 1060 industrial pure aluminum onto the outside of the pretreated Invar core. The cladding temperature is controlled at 420-450℃, forming an aluminum-clad Invar single wire. After continuous extrusion cladding, the resulting single wire is placed in a heat treatment furnace and held at 180℃ for 2 hours, followed by air cooling to room temperature to complete the low-temperature aging treatment.
[0041] S4. The aluminum-clad Invar single wire obtained in step S3 is subjected to micro-arc oxidation treatment to form an anodic oxide layer on the outer surface of the aluminum layer. The micro-arc oxidation treatment adopts a constant current mode, and the electrolyte contains α-Al2O3 nanoparticles. After treatment, the thickness of the anodic oxide layer is 0.16 mm. Subsequently, a graphene oxide dispersion is prepared and coated on the surface of the anodic oxide layer. After drying and reduction treatment, a graphene reinforcement layer is formed with a thickness of 0.08 mm and a graphene purity of not less than 99.5%, thereby forming a composite anti-corrosion layer on the outside of the aluminum layer.
[0042] S5. The aluminum-clad Invar single wires obtained in step S4 are concentrically stranded and combined with untwisting treatment. After stranding, a low-temperature curing treatment is performed to obtain a comparative aluminum-clad Invar stranded wire.
[0043] Comparative Example 2: Preparation and performance of aluminum-clad Invar stranded wire under the condition of setting a zinc alloy transition layer but not constructing a composite anti-corrosion layer.
[0044] S1. Take 3.45 kg of nickel, 0.06 kg of chromium, 0.075 kg of cobalt, and 0.1075 kg of molybdenum, with the total amount of other impurity elements controlled within 0.01 kg. Melt the above raw materials under argon protection, and after melting, cast them into ingots; the resulting ingots are hot-worked to form wire blanks, and then cold-drawn and heat-treated to obtain Invar steel cores with a diameter of 2.50 mm.
[0045] S2. Take 8.15 kg of zinc, 1.55 kg of aluminum, and 0.055 kg of trace rare earth elements, wherein the trace rare earth elements are cerium and lanthanum, with a mass ratio of cerium to lanthanum of 2.0:1, corresponding to approximately 0.0367 kg of cerium and approximately 0.0183 kg of lanthanum. Melt the zinc, aluminum, and trace rare earth elements uniformly in a smelting apparatus at 450–470°C, and then perform degassing treatment to obtain a zinc alloy melt. After pickling, cleaning, and preheating treatment, the Invar core obtained in step S1 is subjected to a hot-dip galvanizing process to form a zinc alloy transition layer on its surface. The hot-dip galvanizing temperature is controlled at 455–460°C, and the thickness of the resulting zinc alloy transition layer is 0.34 mm.
[0046] S3. Using 1060 industrial pure aluminum as the cladding material, a continuous extrusion cladding process is employed to clad the 1060 industrial pure aluminum onto the outside of the zinc alloy transition layer. The cladding temperature is controlled at 420–450°C, resulting in an aluminum-clad Invar single wire with an outer aluminum coating. After continuous extrusion cladding, the resulting single wire is placed in a heat treatment furnace and held at 180°C for 2 hours, followed by air cooling to room temperature to complete the low-temperature aging treatment.
[0047] S4. No micro-arc oxidation treatment, nor graphene coating and reduction treatment are performed. That is, no anodic oxide layer and graphene reinforcement layer are formed on the outer surface of the aluminum layer. The aluminum-clad Invar single wire directly enters the subsequent stranding process after low-temperature aging treatment.
[0048] S5. The aluminum-clad Invar single wires obtained in step S4 are concentrically stranded and combined with untwisting treatment. After stranding, a low-temperature curing treatment is performed to obtain a comparative aluminum-clad Invar stranded wire.
[0049] Performance testing 1. Interfacial shear strength and peel strength test Interfacial shear strength test method: Five sets of 100mm long samples were cut from the aluminum-clad Invar cores obtained in the examples and comparative examples. End burrs were removed and the surfaces were cleaned. An electronic universal testing machine was used to fix the aluminum layer and apply an axial pushing load to the Invar core. The loading speed was controlled at 1mm / min. The maximum load at which relative slippage or failure occurred at the interface was recorded. The interfacial shear strength was calculated based on the interface contact area, and the average value of the five sets of samples was taken as the test result.
[0050] Peel strength test method: Take 5 groups of samples with a length of 100mm, partially peel off the aluminum layer at one end of the sample to form the peel end, and perform a 180° peel test on an electronic universal testing machine. The loading speed is controlled at 50mm / min. Record the average load in the stable peel stage and convert it into peel strength per unit width. Take the average value of 5 groups of samples as the test result.
[0051] The results are shown in Table 1 below.
[0052] Table 1 Interfacial Shear Strength and Peel Strength
[0053] As shown in Table 1, the interfacial shear strength and peel strength of Examples 1-3 are significantly higher than those of Comparative Example 1. This indicates that the zinc alloy transition layer between the Invar core and the aluminum layer effectively improves the interfacial compatibility and bonding state, promotes interfacial atomic diffusion, reduces the interfacial oxide layer and stress concentration, thereby significantly improving the bonding strength between the aluminum layer and the Invar core. Example 2 exhibits the highest interfacial shear strength and peel strength, indicating that the interfacial reinforcement effect is more pronounced under conditions of higher component ratios and thicker layer structures. Furthermore, the test results of Example 3 are higher than those of Comparative Example 2, demonstrating that the composite anti-corrosion layer helps maintain interfacial stability without weakening the interfacial bonding performance.
[0054] 2. Neutral salt spray test Three sets of 150mm long aluminum-clad Invar stranded wire samples were taken from the examples and comparative examples. The surfaces were cleaned with anhydrous ethanol and dried before being placed in a neutral salt spray test chamber. The test solution was a 5% sodium chloride solution, with a pH value controlled at 6.5–7.2. The chamber temperature was controlled at 35±2℃, the salt spray deposition rate was controlled at 1–2 mL / 80cm²·h, and the continuous spraying time was 480h. After the test, the samples were removed, gently rinsed with deionized water to remove surface salt, and dried. The corrosion morphology of the sample surface was observed, and the corrosion area ratio and mass loss rate were recorded. The results are shown in Table 2 below.
[0055] Table 2 Results of Neutral Salt Spray Test
[0056] As shown in Table 2, after 480 hours of neutral salt spray testing, the corrosion area ratio and mass loss rate of each embodiment of the present invention were significantly lower than those of the comparative examples. Example 2 showed the best performance, with a corrosion area ratio of only 1.5% and a mass loss rate of 0.12%, maintaining a clean surface without significant corrosion. Examples 1 and 3 exhibited slight pitting corrosion, but their surface structures remained intact. Comparative Example 1, lacking a zinc alloy transition layer, had weaker interfacial bonding, making it prone to corrosion channels, resulting in a significantly higher degree of corrosion than the examples. Comparative Example 2, without a composite anti-corrosion layer, had its aluminum layer directly exposed to the corrosive environment, leading to a significant increase in both corrosion area and mass loss, and the accumulation of obvious corrosion products.
[0057] 3. Interfacial strength retention rate test after thermal cycling Five sets of 100mm long samples were cut from the aluminum-clad Invar single-wire specimens obtained in the examples and comparative examples. The surfaces were cleaned with anhydrous ethanol and dried. The initial interfacial shear strength was measured according to the interfacial shear strength test method. Another set of specimens of the same specifications were placed in a thermal cycling chamber and subjected to cyclic testing between room temperature and 180℃. Each cycle included heating to 180℃ and holding for 30 minutes, followed by cooling to room temperature and holding for 30 minutes, for a total of 50 cycles. After the thermal cycling was completed, the specimens were cooled to room temperature, and the interfacial shear strength after thermal cycling was tested using the same method. The interfacial strength retention rate was calculated, and the average value of the five sets of specimens was taken as the test result. The results are shown in Table 3 below.
[0058] Table 3 Results of interfacial strength retention after thermal cycling
[0059] As shown in Table 3, Examples 1-3 maintained a high interfacial shear strength retention rate after 50 thermal cycles, significantly better than Comparative Examples 1 and 2, indicating that the interfacial structure constructed by this invention has good stability under repeated temperature changes. Specifically, Examples 2 and 3 achieved retention rates of 93.9% and 92.1%, respectively, indicating that the zinc alloy transition layer effectively alleviates the interfacial stress concentration caused by the difference in thermal expansion between the aluminum layer and the Invar core, reducing the occurrence of interfacial microcracks and delamination during thermal cycling. Although Example 1 had a lower component ratio and thinner layer structure, its retention rate still reached 89.7%, demonstrating the good applicability of this invention under different parameter conditions. In contrast, Comparative Example 1, lacking a zinc alloy transition layer, showed the most significant decrease in interfacial strength after thermal cycling; Comparative Example 2, although having a transition layer, did not construct a composite anti-corrosion layer, and its retention rate was still lower than that of Examples 1-3, indicating that this invention, through the synergistic design of interfacial strengthening and surface protection, can further improve the long-term service stability of aluminum-clad Invar strands.
[0060] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0061] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.
Claims
1. A high-interfacial bonding strength aluminum-clad Invar stranded wire, characterized in that, The aluminum-clad Invar stranded wire comprises a stranded wire structure formed by stranding several aluminum-clad Invar single wires. The aluminum-clad Invar single wire, from the inside out, includes an Invar core, a zinc alloy transition layer, an aluminum layer, and a composite anti-corrosion layer. The Invar steel core is made from the following raw materials, by weight: 33.5-35.5 parts nickel, 0.5-0.7 parts chromium, 0.6-0.9 parts cobalt, 1.0-1.15 parts molybdenum, and other impurity elements totaling no more than 0.10 parts, with the balance being iron. The zinc alloy transition layer is made of the following raw materials, by mass: 78-85 parts zinc, 12-19 parts aluminum, 0.3-0.8 parts trace rare earth elements, and unavoidable impurities, the total amount of which is no more than 1.2 parts. The aluminum layer is 1060 industrial pure aluminum, made from the following raw materials, by mass, including: no more than 0.25 parts silicon, no more than 0.35 parts iron, no more than 0.05 parts copper, no more than 0.10 parts other impurities, and the balance being aluminum; The composite anti-corrosion layer consists of an inner anodic oxide layer and an outer graphene reinforcement layer.
2. The aluminum-clad Invar stranded wire with high interfacial bonding strength according to claim 1, characterized in that, The trace rare earth element in the zinc alloy transition layer is a mixture of cerium and lanthanum, with a mass ratio of cerium to lanthanum of 1.8 to 2.2:1, and the amount of cerium used is 0.2 to 0.53 parts, and the amount of lanthanum used is 0.1 to 0.27 parts.
3. The aluminum-clad Invar stranded wire with high interfacial bonding strength according to claim 1, characterized in that, The thickness of the zinc alloy transition layer is 0.18–0.50 mm.
4. The aluminum-clad Invar stranded wire with high interfacial bonding strength according to claim 1, characterized in that, In the composite anti-corrosion layer, the thickness of the anodic oxide layer is 0.12-0.20 mm, the thickness of the graphene reinforcement layer is 0.06-0.10 mm, and the ratio of the thickness of the zinc alloy transition layer to the thickness of the anodic oxide layer is 1.5-2.5:
1.
5. The aluminum-clad Invar stranded wire with high interfacial bonding strength according to claim 1, characterized in that, The graphene in the graphene reinforcement layer is obtained by reducing graphene oxide, and the purity of the graphene is not less than 99.5%.
6. A method for preparing aluminum-clad Invar stranded wire with high interfacial bonding strength as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Weigh each raw material, and carry out smelting, casting, hot working, cold drawing and heat treatment to obtain Invar steel core; S2. After pretreatment of the Invar core, a zinc alloy transition layer is formed on the surface of the Invar core using a hot-dip galvanizing process; S3. An aluminum layer is coated onto the outside of the zinc alloy transition layer using a continuous extrusion coating process to obtain an aluminum-clad Invar single wire; S4. The aluminum layer surface of the aluminum-clad Invar single wire is first subjected to micro-arc oxidation treatment to form an anodic oxide layer, and then graphene coating and reduction treatment are performed to form a graphene reinforcement layer, thereby obtaining an aluminum-clad Invar single wire with a composite anti-corrosion layer. S5. Twist multiple aluminum-clad Invar single wires together to obtain the aluminum-clad Invar stranded wire with high interfacial bonding strength.
7. The preparation method according to claim 6, characterized in that, In step S2, the pretreatment includes pickling, cleaning and preheating; the zinc alloy melt used in the hot-dip galvanizing process is obtained by smelting the following raw materials: 78-85 parts zinc, 12-19 parts aluminum, 0.3-0.8 parts trace rare earth elements, and unavoidable impurities, and is degassed after smelting.
8. The preparation method according to claim 6, characterized in that, In step S3, after continuous extrusion coating is completed, the obtained aluminum-clad Invar single wire is subjected to low-temperature aging treatment; in step S5, the stranding adopts concentric stranding combined with untwisting treatment, and after stranding is completed, low-temperature curing treatment is performed.
9. The preparation method according to claim 6, characterized in that, In step S4, the micro-arc oxidation treatment adopts a constant current mode, and the micro-arc oxidation electrolyte is doped with α-Al2O3 nanoparticles. The graphene coating and reduction treatment includes: preparing a graphene oxide dispersion, coating it on the surface of the anodic oxide layer, drying it, and then performing a reduction treatment to form a graphene reinforcement layer.
10. The preparation method according to claim 6, characterized in that, The graphene oxide dispersion was prepared by adding graphene oxide to deionized water, then adding a dispersant, and then dispersing it by ultrasound to obtain a uniform dispersion.