A manufacturing method of a track socket busbar, a composite busbar and a track socket

Abstract

The application relates to the technical field of power connection device manufacturing, in particular to a manufacturing method of a track socket busbar, a composite busbar and a track socket, and aims to solve the problems that although a traditional silver plating process can delay copper-based oxidation, the silver layer is easy to wear and the cost is high, and although a micro-arc oxidation layer of an aluminum-based busbar has insulation, a porous structure is easy to absorb moisture, leading to a decrease in corrosion resistance. The application forms a silver-nickel alloy layer with metallurgical bonding through laser surface alloying, generates an in-situ ceramic insulation layer through micro-arc oxidation, and realizes stable compounding of copper-aluminum substrates by using a mechanical occlusion structure, so that the advantages of synchronously improving the electric conductivity and the corrosion resistance and solving the interface delamination problem are achieved.

Description

Technical Field

[0001] This application relates to the field of power connection device manufacturing technology, and more specifically, to a method for manufacturing a rail socket busbar, a composite busbar, and a rail socket. Background Technology

[0002] Currently, the manufacturing of rail switch busbars faces two major technical challenges: First, the busbar material is prone to oxidation during long-term use, and a high-resistivity copper oxide layer will form on the surface of the copper-based material. This not only significantly increases the contact resistance, but also leads to a continuous deterioration of conductivity, which seriously affects the reliability of equipment operation.

[0003] While traditional silver plating can slow down the oxidation process to some extent, it has inherent drawbacks such as easy wear of the silver layer and high cost. Although aluminum-based busbars have the advantage of being lightweight, their electrochemical corrosion problems are particularly prominent in humid environments. More importantly, the existing interface bonding technology for copper-aluminum composite busbars has significant shortcomings. Under long-term mechanical stress and thermal cycling, interface delamination is prone to occur, further exacerbating the risk of contact failure.

[0004] Secondly, existing surface treatment technologies have significant limitations. Traditional methods such as electroplating and hot-dip plating struggle to achieve uniform coating coverage, and the bonding strength between the coating and the substrate is often insufficient. For example, silver plating easily produces uneven silver layers, leading to excessively high local current densities; hot-dip tin plating poses a safety hazard due to tin whisker growth. Although micro-arc oxidation technology can provide a ceramic insulation layer for aluminum-based busbars, a single surface treatment method cannot simultaneously meet the dual requirements of conductivity and corrosion resistance, severely restricting the overall performance improvement of rail socket busbars.

[0005] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0006] (a) Technical problems to be solved To address the aforementioned issues, this invention proposes a method for manufacturing a track socket busbar, a composite busbar, and a track socket. The aim is to solve the problems that while traditional silver plating can delay copper-based oxidation, the silver layer is easily worn and costly, and while the micro-arc oxide layer of aluminum-based busbars has insulation properties, its porous structure easily absorbs moisture, leading to a decrease in corrosion resistance.

[0007] (II) Technical Solution The present invention provides a method for manufacturing a track socket busbar, the technical solution of which is as follows: the copper-based components of the busbar include: The manufacturing method comprises 98.5–99.5 wt% copper matrix, 0.4–1.2 wt% silver-nickel alloy powder, and 0.03–0.06 wt% grain boundary strengthening additives. The core process steps are described below, and each step synergistically improves both electrical conductivity and corrosion resistance: S1, Copper-based busbar pretreatment and laser surface alloying are combined. First, the surface of the copper-based busbar is polished to remove oxide scale, and then the oil is removed by ultrasonic cleaning with ethanol. Subsequently, a green laser is used for surface alloying, and the silver-nickel alloy powder is fused onto the surface of the copper-based busbar to form a silver-nickel alloy layer with a thickness of 10-20 μm that is bonded to the copper-based metallurgy. The surface roughness Ra of the silver-nickel alloy layer is 1.5-2.0 μm. S2, aluminum-based busbar pretreatment and micro-arc oxidation synergistic treatment, the aluminum-based busbar is subjected to alkaline degreasing and acid washing activation in sequence; Subsequently, micro-arc oxidation is carried out in an electrolyte containing 15-20 g / L sodium silicate, 2-5 g / L potassium hydroxide, and 3-6 g / L sodium fluoride, using a stepped voltage control to generate a ceramic insulating layer that bonds in situ with the aluminum substrate; finally, the pores are sealed by boiling water impregnation to ensure that the water absorption rate of the ceramic insulating layer is ≤0.1%. S3, Composite Assembly: The copper-based busbar treated by S1 is combined with the aluminum-based busbar treated by S2 and fixed by bolt connection, snap-fit ​​connection or laser welding. The silver-nickel alloy layer of the copper-based busbar and the ceramic insulation layer of the aluminum-based busbar form a mechanical interlocking structure. The mechanical interlocking structure is formed by the predetermined roughness of the silver-nickel alloy layer and the porous growth morphology of the ceramic insulation layer, and finally a composite busbar is obtained.

[0008] Furthermore, the grain boundary strengthening additive is trimethyl borate or triethyl phosphate, which is uniformly mixed with silver-nickel alloy powder before laser surface alloying. The additive decomposes to generate active elements during the laser cladding process, which react with oxygen and sulfur impurities at the copper-based grain boundaries, so that the content of copper-based grain boundary impurities is ≤10ppm.

[0009] Furthermore, the silver-nickel alloy powder in S1 has a silver-nickel mass ratio of 7:3 to 9:1, and the laser process parameters are as follows: Power 600-800W, scanning speed 5-10mm / s, spot diameter 0.4-0.6mm, energy density 15-35J / cm².

[0010] Furthermore, after laser surface alloying in S1, chemical passivation treatment is also included: the silver-nickel alloy layer is immersed in a chromate solution to form a passivation film with a thickness of 0.5-1.0 μm on its surface. The passivation film increases the salt spray resistance time of the silver-nickel alloy layer by 20-30%.

[0011] Furthermore, the ceramic insulating layer of S2 with micro-arc oxidation has a thickness of 15-25μm, a hardness of 1000-2000HV, and an insulation resistance of ≥100MΩ. The ceramic insulating layer is mainly composed of Al2O3 and contains 5-8wt% SiO2 to reduce the internal stress of the film.

[0012] Furthermore, S2 also includes micro-arc oxidation auxiliary parameters for cooperating with the stepped voltage control, wherein the micro-arc oxidation auxiliary parameters are a frequency of 500-1000Hz, a duty cycle of 8-12%, and an oxidation time of 8-20min.

[0013] Furthermore, the composite assembly in S3 also includes an interface reinforcement step: Apply thermally and electrically conductive adhesive to the interface between the copper-based and aluminum-based components, and then cure at 80-100℃ for 30-45 minutes to ensure that the interfacial contact resistance of the composite busbar is ≤5×10⁻⁶. -6 Ω・cm.

[0014] Furthermore, this application also proposes a composite busbar for a track socket, manufactured using the manufacturing method described in any one of claims 1-7, wherein the composite busbar comprises: A copper substrate with a silver-nickel alloy layer on its surface, wherein the silver-nickel alloy layer is metallurgically bonded to the copper substrate. An aluminum substrate with a ceramic insulating layer on its surface, wherein the ceramic insulating layer is bonded to the aluminum substrate in situ. The copper base and the aluminum base are fixed by bolts, clips or laser welding, and the silver-nickel alloy layer and the ceramic insulating layer form a mechanical interlocking interface.

[0015] Furthermore, the thickness of the copper base is 0.8-1.5mm, the thickness of the aluminum base is 1.2-2.0mm, the thickness deviation of the silver-nickel alloy layer is ≤±2μm, and the thickness deviation of the ceramic insulation layer is ≤±3μm, ensuring that the overall flatness of the composite busbar is ≤0.1mm / m.

[0016] Furthermore, this application also proposes a track socket, characterized in that it includes the composite busbar as described in claim 8 or 9, the composite busbar being disposed within the conductive channel of the socket, with its two ends respectively connected to the input terminal and output terminal of the socket; the socket further includes an insulating housing, the insulating housing having heat dissipation holes corresponding to the position of the composite busbar. Furthermore, this application also proposes a track socket, characterized in that it includes the composite busbar as described in claim 8 or 9, the composite busbar being disposed within the conductive channel of the socket, with its two ends respectively connected to the input terminal and output terminal of the socket; the socket further includes an insulating housing, the insulating housing having heat dissipation holes corresponding to the position of the composite busbar. Furthermore, this application also proposes a track socket, characterized in that it includes the composite busbar as described in claim 8 or 9, the composite busbar being disposed within the conductive channel of the socket, with its two ends respectively connected to the input terminal and output terminal of the socket; the socket further includes an insulating housing, the insulating housing having heat dissipation holes corresponding to the position of the composite busbar.

[0017] (III) Beneficial Effects Compared with the prior art, the beneficial effects of the present invention are as follows: In this invention, a metallurgically bonded silver-nickel alloy layer is formed by laser surface alloying, an in-situ ceramic insulating layer is generated by micro-arc oxidation, and a stable composite of copper and aluminum substrate is achieved by mechanical interlocking structure. This invention has the advantages of simultaneously improving conductivity and corrosion resistance, and solving the problem of interface delamination.

[0018] This invention achieves a simultaneous improvement in the oxidation resistance of copper-based busbars and the corrosion resistance of aluminum-based busbars, while effectively suppressing delamination through an interfacial mechanical interlocking structure. The copper-aluminum composite busbar, while maintaining high conductivity, significantly extends its service life in humid environments, solving the problem of balancing conductivity and interfacial stability in traditional processes. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A schematic diagram of the process structure for manufacturing the motherboard; Figure 2 This is a schematic diagram of the connection structure between the track and the busbar; Figure 3 This is a schematic diagram of the three-dimensional structure of the busbar.

[0021] 1. Insulating outer shell, 2. Conductive channel, 3. Composite busbar, 31. Copper base, 32. Aluminum base. Detailed Implementation

[0022] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. It should be noted that similar reference numerals and letters in the following drawings indicate similar items; therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] In existing technologies, track socket busbars have long faced problems such as increased contact resistance and insufficient interfacial bonding strength due to oxidation. While traditional silver plating can delay copper-based oxidation, the silver layer is easily worn and expensive. Although the micro-arc oxide layer of aluminum-based busbars has insulation properties, its porous structure easily absorbs moisture, leading to decreased corrosion resistance. Copper-aluminum composite busbars are often directly welded or glued, but due to differences in thermal expansion coefficients, interfacial delamination is prone to occur, affecting long-term stability.

[0024] This study considers constructing an alloy layer with both conductivity and oxidation resistance on a copper-based surface, while simultaneously forming an insulating layer with low water absorption on an aluminum-based surface, and achieving mechanical bonding through interface structure design. By analyzing the characteristics of laser surface alloying and micro-arc oxidation processes, it was found that laser cladding can form a metallurgical bonding layer with a specific roughness, while the porous ceramic layer generated by micro-arc oxidation can provide anchoring points. The complementary morphologies of the two may overcome the interface bonding bottleneck of traditional copper-aluminum composites.

[0025] Therefore, as Figure 1 As shown, this application proposes the following manufacturing method: S1, Copper-based busbar pretreatment and laser surface alloying synergistic treatment: First, the surface of the copper-based busbar is polished to remove oxide scale, and then the oil is removed by ultrasonic cleaning with ethanol. Subsequently, a green laser is used for surface alloying, and the silver-nickel alloy powder is fused onto the surface of the copper-based busbar to form a silver-nickel alloy layer with a thickness of 10-20 μm that is bonded to the copper-based metallurgy. The surface roughness Ra of the silver-nickel alloy layer is 1.5-2.0 μm.

[0026] The copper-based components are formulated in the following mass ratio: 98.5–99.5 wt% copper matrix, 0.4–1.2 wt% silver-nickel alloy powder, and 0.03–0.06 wt% grain boundary strengthening additives.

[0027] During pretreatment, the copper-based surface is sanded step-by-step until the oxide scale is completely removed, followed by ultrasonic cleaning in an ethanol solution to ensure that the residual oil on the surface is ≤0.01g / m². Laser surface alloying uses a green laser with the following process parameters: power 600-800W, scanning speed 5-10mm / s, spot diameter 0.4-0.6mm, and energy density 5-35J / cm². After cladding, a silver-nickel alloy layer with a thickness of 10-20μm and a surface roughness Ra of 1.5-2.0μm is formed, and a metallurgical bonding diffusion layer with a depth of 3-5μm is formed with the copper base.

[0028] S2, Aluminum-based busbar pretreatment and micro-arc oxidation synergistic treatment: The aluminum-based busbar is subjected to alkaline degreasing and acid washing activation in sequence; Subsequently, micro-arc oxidation is carried out in an electrolyte containing 15-20 g / L sodium silicate, 2-5 g / L potassium hydroxide, and 3-6 g / L sodium fluoride. A stepped voltage control is used to generate a ceramic insulating layer that is in situ bonded to the aluminum substrate. Finally, the ceramic insulating layer is sealed by boiling water immersion to achieve a water absorption rate of ≤0.1%.

[0029] Alkaline degreasing is performed using a 5-10 g / L NaOH solution, soaking at 50-60℃ for 5-8 minutes; acid pickling and activation are performed using a 10-15% HNO3 solution, soaking at room temperature for 3-5 minutes, resulting in a contact angle of ≤30° on the aluminum substrate surface. The micro-arc oxidation electrolyte consists of 15-20 g / L sodium silicate, 2-5 g / L potassium hydroxide, and 3-6 g / L sodium fluoride, controlled by a stepped voltage: pre-oxidation at 250-350V for 3-8 seconds, followed by main oxidation at 400-500V for 8-20 minutes, with auxiliary parameters of a frequency of 500-1000Hz and a duty cycle of 8-12%. Boiling water sealing is performed at 95-100℃ for 25-35 minutes, resulting in a ceramic insulation layer with a water absorption rate of ≤0.1%, a thickness of 15-25 μm, and a hardness of 1000-2000 HV.

[0030] S3, Composite Assembly: The copper-based busbar treated by S1 is combined with the aluminum-based busbar treated by S2 and fixed by bolt connection, snap connection or laser welding. The silver-nickel alloy layer of the copper-based busbar and the ceramic insulation layer of the aluminum-based busbar form a mechanical interlocking structure. The mechanical interlocking structure is formed by the predetermined roughness of the silver-nickel alloy layer and the porous growth morphology of the ceramic insulation layer, and finally a composite busbar is obtained.

[0031] The copper-based busbar pretreatment involves removing surface oxide scale and oil stains through physical grinding and ultrasonic cleaning, specifically using sandpaper grinding and ethanol ultrasonic cleaning, to provide a clean substrate for subsequent laser alloying. Laser surface alloying synergistic treatment involves using a high-energy laser beam to clad silver-nickel alloy powder onto the copper-based surface, specifically using a green laser, forming an alloy layer that is metallurgically bonded to the substrate to improve oxidation resistance. Silver-nickel alloy layer surface roughness control involves adjusting laser process parameters to create microscopic protrusions in the cladding layer, specifically by adjusting power and scanning speed, providing an anchoring structure for mechanical engagement.

[0032] The micro-arc oxidation synergistic treatment of aluminum-based busbars refers to the generation of a ceramic insulating layer through an electrochemical reaction in an electrolyte. Specifically, this can be achieved using an electrolyte containing sodium silicate and sodium fluoride, combined with a stepped voltage, to form a surface that combines insulation and a porous structure. The mechanical interlocking structure formation utilizes the interlocking effect of the rough surface of the silver-nickel alloy layer and the porous morphology of the ceramic layer. This can be achieved by controlling the matching degree between the roughness of the alloy layer and the porosity of the ceramic layer, thereby enhancing the interfacial bonding strength.

[0033] Specifically, after pretreatment, the silver-nickel alloy layer formed by laser cladding on the copper-based busbar achieves atomic-level bonding with the substrate, and its surface micro-protrusions provide physical support for subsequent interlocking. The ceramic layer formed by micro-arc oxidation on the aluminum-based busbar has uniform pores; boiling water sealing treatment closes the surface pores while preserving internal interconnected channels. During composite assembly, the protrusions of the silver-nickel alloy layer embed into the pores of the ceramic layer, forming a three-dimensional interlocking structure that effectively disperses interfacial stress. The copper and aluminum bases, through the dual protection of the metallurgical bonding layer and the ceramic layer, simultaneously inhibit oxidation and electrochemical corrosion.

[0034] Traditional methods, when treating copper-based or aluminum-based substrates alone, result in weak adhesion between the coating and the substrate and fail to address interfacial delamination. This solution utilizes a synergistic process of laser alloying and micro-arc oxidation to transform the microstructures created by the two surface treatments into favorable conditions for interfacial bonding, rather than relying on additional adhesive materials. The mechanical interlocking structure overcomes the limitations of thermal expansion coefficients inherent in traditional welding or adhesive bonding, ensuring the stability of the copper-aluminum composite interface during thermal cycling.

[0035] This application achieves a simultaneous improvement in the oxidation resistance of copper-based busbars and the corrosion resistance of aluminum-based busbars, while effectively suppressing delamination through an interfacial mechanical interlocking structure. The copper-aluminum composite busbar, while maintaining high conductivity, significantly extends its service life in humid environments, solving the problem of balancing conductivity and interfacial stability in traditional processes.

[0036] This application further proposes that the grain boundary strengthening additive is trimethyl borate or triethyl phosphate, which is mixed evenly with silver-nickel alloy powder before laser surface alloying. The additive decomposes to generate active elements during the laser cladding process, which react with oxygen and sulfur impurities at the copper-based grain boundaries, thereby controlling the content of copper-based grain boundary impurities to below 10 ppm.

[0037] The grain boundary strengthening additive refers to a compound that can decompose at high temperatures and react with grain boundary impurities. Specifically, it can be trimethyl borate or triethyl phosphate. Trimethyl borate decomposes to generate boron during laser cladding, and triethyl phosphate decomposes to generate phosphorus. The active element refers to boron or phosphorus, which is generated through thermal decomposition during laser cladding. The active element preferentially combines with oxygen and sulfur at the copper-based grain boundaries to form stable compounds. Uniform mixing refers to the physical mixing of the additive and silver-nickel alloy powder before laser cladding. This can be achieved using mechanical stirring or ball milling to ensure that the active element diffuses into the grain boundary region with the molten pool during the cladding process.

[0038] Specifically, during laser surface alloying, silver-nickel alloy powder and additives are heated and melted together to form a molten pool. Boron or phosphorus elements produced by the decomposition of the additives diffuse to the copper substrate surface along with the flow of the molten pool. Because the melting point of the silver-nickel alloy is lower than that of the copper substrate, the decomposition products of the additives are preferentially encapsulated during molten pool formation, preventing active elements from floating or sinking due to density differences. Within the molten pool, the active elements react chemically with oxygen and sulfur impurities at the copper substrate grain boundaries, generating borate or phosphate compounds. These compounds are discharged as slag or dissolved in the substrate. By controlling the amount of additives and laser process parameters, oxygen and sulfur impurities in the grain boundary region are effectively removed, improving the continuity of electron migration channels at the grain boundaries.

[0039] Traditional grain boundary refining methods rely on high-temperature annealing or vacuum melting processes, which suffer from high equipment costs and long process cycles. However, by employing a synergistic approach of additives and laser cladding, grain boundary refining can be achieved under normal atmospheric conditions. Existing grain boundary strengthening additives are mostly used in high-temperature alloys, neglecting the process compatibility with copper-based busbars. This solution selects additives with specific decomposition temperatures, allowing them to precisely release active elements at the instantaneous high temperature of laser cladding. This avoids premature decomposition leading to activity loss and prevents unreacted additive residues from affecting conductivity.

[0040] This application achieves highly efficient removal of copper-based grain boundary impurities, reducing electron migration resistance and the risk of intergranular corrosion. The conductivity of the copper-based busbar is significantly improved due to the reduction of grain boundary impurities, and the stability of contact resistance is enhanced. Simultaneously, the reduction in oxygen and sulfur content at the grain boundaries effectively inhibits electrochemical corrosion in humid environments, extending the service life of the busbar. This solution, without adding extra process steps, solves the problem of balancing purification effectiveness and process economy that traditional methods struggle to address by optimizing the types of additives and mixing methods.

[0041] This application further proposes that the silver-nickel alloy powder has a silver-nickel mass ratio of 7:3 to 9:1, and the laser process parameters include a power of 600-800W, a scanning speed of 5-10mm / s, a spot diameter of 0.4-0.6mm, and an energy density of 15-35J / cm².

[0042] The silver-nickel mass ratio of 7:3 to 9:1 refers to the range of mass percentages of silver and nickel in the alloy powder. This can be achieved by mechanically mixing silver and nickel powder in this ratio and then ball-milling the resulting alloy powder. This ratio range ensures that the liquidus temperature of the alloy powder matches the temperature of the laser molten pool, avoiding unmelted particles or melt flow issues. The laser power of 600-800W refers to the energy intensity range of the laser output, which can be achieved using a fiber laser with a power adjustment module. This power range, in conjunction with the spot diameter, controls the energy input per unit area, preventing overheating of the substrate or insufficient cladding. The scanning speed of 5-10mm / s refers to the rate at which the laser beam moves across the copper substrate surface, which can be achieved using a motion control system on a CNC worktable. This speed range matches the cooling rate of the molten pool, ensuring sufficient melt spread and suppressing elemental segregation. The spot diameter of 0.4-0.6mm refers to the size of the area of ​​effect after the laser beam is focused, which can be achieved by adjusting the beam focus position using a lens group. This size range, combined with the power, forms a stable molten pool, ensuring uniform coating thickness. The energy density of 15-35 J / cm² refers to the laser energy input per unit area, which can be calculated using the ratio of power, scanning speed, and spot diameter. This parameter range ensures a metallurgical bond between the silver-nickel alloy layer and the copper substrate, while controlling the depth of the heat-affected zone.

[0043] Specifically, the choice of silver-nickel mass ratio ensures that the liquidus temperature of the alloy powder matches the temperature range of the laser-melted pool. When the silver content is between 70% and 90%, the alloy liquidus temperature decreases to near the melting point of the copper base, forming a homogeneous melt under laser irradiation and undergoing a eutectic reaction with the copper base, creating a metallurgically bonded zone with controllable depth. The combination of laser power and spot diameter limits the energy density to the range of 15-35 J / cm², avoiding both excessive energy leading to coarsening of the copper base grains and insufficient energy causing incomplete melting of the powder. The coordinated control of scanning speed and energy density maintains a stable flow state in the molten pool, ensuring uniform spreading of the silver-nickel alloy layer on the copper base surface while suppressing local enrichment of nickel. Precise control of the spot diameter further constrains the molten pool size, keeping the coating thickness deviation at a low level.

[0044] Traditional laser cladding processes often employ a single silver-based alloy or a fixed silver-nickel ratio, and the laser parameter settings lack a systematic approach. For example, while pure silver plating offers excellent conductivity, it suffers from insufficient corrosion resistance; alloys with a silver-nickel ratio lower than 7:3 result in incomplete cladding due to their excessively high melting points. This solution, by precisely matching the silver-nickel ratio with laser parameters, achieves uniform composition distribution and stable interfacial bonding during alloy layer formation, overcoming the problems of high plating porosity and low bonding strength found in traditional processes.

[0045] This application effectively solves the problem of poor coating uniformity caused by process parameter mismatch during laser cladding of silver-nickel alloy layers, while balancing the requirements of conductivity and corrosion resistance. The metallurgical bonding strength between the coating and the substrate is significantly improved, avoiding the risk of interface delamination, and the uniform distribution of alloy composition reduces the phenomenon of local resistance increase. The coordinated control of laser parameters further ensures that the surface roughness of the coating meets the processing requirements of subsequent mechanical interlocking structures.

[0046] This application further proposes adding a chemical passivation step after laser surface alloying, in which the silver-nickel alloy layer is immersed in a chromate solution to form a passivation film of a predetermined thickness.

[0047] The chromate solution refers to an aqueous solution primarily composed of chromate ions. Specifically, a sodium chromate or potassium chromate solution with a concentration of 5-8 grams per liter can be used. This concentration range balances the passivation reaction rate and solution stability. The passivation film thickness is controlled within the range of 0.5-1.0 micrometers, which can be achieved by adjusting the immersion time and solution concentration. This thickness range effectively blocks the penetration of corrosive media while avoiding a decrease in conductivity due to excessive film thickness.

[0048] Specifically, during the passivation process, chromate ions react chemically with the metal oxides on the surface of the silver-nickel alloy layer to form a composite oxide film. This film is chemically bonded to the silver-nickel alloy layer, forming a stable interface structure. The immersion time is controlled at 8-12 minutes to ensure the reaction proceeds fully without causing excessive corrosion of the substrate. The passivation film formation process and the laser alloying process create a synergistic effect, constructing a chemical protective barrier while maintaining the high conductivity of the silver-nickel alloy layer.

[0049] Traditional processes often employ electroplating hard chrome or organic coatings to improve corrosion resistance. However, the former poses environmental pollution risks and affects conductivity, while the latter is prone to peeling and cannot withstand high current loads. This solution combines chemical passivation with laser alloying to form an ultra-thin protective layer under pollution-free conditions. This overcomes the shortcomings of traditional plating processes and avoids the insulation problems of organic coatings.

[0050] This application effectively solves the corrosion problem of the silver-nickel alloy layer in humid and chlorine-containing environments, significantly extending the service life of the busbar under complex working conditions. The chemical bonding mechanism between the passivation film and the alloy layer ensures the stability of the protective layer under mechanical stress and temperature changes, while maintaining the low contact resistance characteristics of the busbar, meeting the dual requirements of conductivity and corrosion resistance for rail sockets.

[0051] This application further proposes forming a ceramic insulating layer in a micro-arc oxidation process. The thickness of the ceramic insulating layer is controlled in the range of 15-25 μm, the hardness is maintained in the range of 1000-2000 HV, and the insulation resistance is not less than 100 MΩ. Its main component is alumina and contains 5-8 wt% silicon dioxide to reduce the internal stress of the film layer.

[0052] The thickness range of the ceramic insulating layer refers to the longitudinal dimension of the film formed by controlling the micro-arc oxidation time and voltage parameters. This can be achieved using a stepped voltage adjustment method. This thickness range ensures both the insulating barrier function and prevents brittle fracture. The hardness index refers to the ceramic layer's resistance to external mechanical forces, which can be achieved by adjusting the electrolyte composition and discharge parameters. This hardness range ensures scratch resistance. The lower limit of insulation resistance refers to the ceramic layer's ability to block current, which is achieved by optimizing the film density and compositional uniformity. This index directly ensures the reliability of electrical insulation. The silica content refers to the silicon doping ratio in the alumina matrix, which is achieved by controlling the silicate concentration in the electrolyte. This ratio alleviates internal stress through phase structure regulation.

[0053] Specifically, when an alumina-based ceramic layer is formed on the surface of the aluminum-based busbar, the introduction of silica promotes the formation of a composite phase structure. Alumina provides basic hardness and insulation properties, while silica undergoes a high-temperature phase transformation to form a glassy phase that fills the grain boundary pores, while simultaneously generating a mullite phase to refine the grains. This synergistic effect of the phase structure allows the ceramic layer to reduce internal stress while maintaining high hardness, preventing crack propagation due to increased thickness. The matching design of the film thickness and hardness enables it to withstand mechanical compression during installation, while the insulation resistance setting ensures effective blocking of leakage current paths at rated voltage.

[0054] Traditional micro-arc oxidation processes result in pure alumina films with internal stress concentration, which easily leads to cracking when the thickness exceeds 20 μm. While high silica content glassy films can reduce stress, they lack sufficient hardness. This solution precisely controls the silica content to construct a multiphase composite structure within the alumina matrix. This maintains the high hardness and insulation of the ceramic layer while effectively dispersing internal stress through microstructure optimization, resolving the technical contradiction of balancing hardness and stress in traditional processes.

[0055] This application can form a ceramic insulation layer with both high mechanical strength and low internal stress, which can effectively resist the cracking of the film layer caused by installation stress and environmental temperature changes during long-term use of the rail socket busbar, while ensuring stable electrical insulation performance, avoiding the risk of leakage due to insulation failure, and significantly improving the reliability and service life of the composite busbar.

[0056] This application further proposes that when performing micro-arc oxidation in an electrolyte, a stepped voltage control is used in conjunction with auxiliary parameters such as a frequency of 500-1000Hz, a duty cycle of 8-12%, and an oxidation time of 8-20min.

[0057] In this context, frequency refers to the number of discharges of the pulse power supply during the micro-arc oxidation process. This can be achieved using a frequency-adjustable pulse power supply, where the intensity of plasma discharge is controlled by adjusting the frequency. Duty cycle refers to the ratio of the high-level duration within a single pulse cycle to the total cycle length. This can be achieved using an adjustable duty cycle circuit, where the energy input intensity per unit time is controlled by adjusting the duty cycle. Oxidation time refers to the total duration of the micro-arc oxidation process, which can be achieved using a timer-linked control device. Setting the oxidation time ensures the integrity of the film growth.

[0058] Specifically, during the pre-oxidation stage, a voltage of 250-350V is used, with the frequency set to a high frequency close to 1000Hz and the duty cycle controlled at a low level of 8%. At this stage, short high-frequency pulses promote the rapid formation of a dense initial oxide layer with low porosity on the aluminum substrate surface. Upon entering the main oxidation stage, the voltage is increased to 400-500V, the frequency gradually decreases to the 500-800Hz range, and the duty cycle increases to the 10-12% range. Long low-frequency pulses provide continuous energy input for the alumina crystal transformation, promoting the formation of the α-Al₂O₃ phase. The oxidation time is set to 8-20 minutes to ensure that both the pre-oxidation and main oxidation stages achieve their respective film growth targets, avoiding insufficient time leading to an excessively thin film or excessive time causing internal stress accumulation.

[0059] Traditional micro-arc oxidation processes typically employ fixed frequency and duty cycle parameters, such as a fixed frequency of 800Hz and a fixed duty cycle of 10%. This parameter setting method cannot adapt to the process requirements of stepped voltage at different stages. In existing technologies, high-frequency discharge in the pre-oxidation stage easily leads to excessive porosity in the initial film layer, while the fixed low frequency in the main oxidation stage makes it difficult to achieve sufficient conversion of α-phase alumina.

[0060] This application achieves dynamic matching of voltage stage and auxiliary parameters during micro-arc oxidation, effectively controlling the pore distribution and crystal phase composition of the ceramic insulating layer, so that the film hardness and insulation performance reach a balanced state, while significantly reducing the performance fluctuation between batches.

[0061] This application further proposes that after the composite assembly, an interface reinforcement step is also included: applying thermally and electrically conductive adhesive to the interface between the copper base and the aluminum base, and then curing it at 80-100℃ for 30-45 minutes, so that the interface contact resistance of the composite busbar is ≤5×10-6Ω・cm.

[0062] Among them, thermally conductive and electrically conductive adhesive refers to adhesive with a thermal conductivity ≥10W / (m・K) and a volume resistivity ≤1×10⁻ 4 The adhesive material with an Ω·cm bonding strength can be achieved using an epoxy resin system filled with silver powder or graphene. Its function is to reduce interfacial temperature rise through high thermal conductivity, while maintaining the stability of the conductive path due to its low electrical resistance. The curing temperature of 80-100℃ refers to the temperature range for the colloidal cross-linking reaction, which can be achieved using gradient heating or a constant temperature oven. Its purpose is to promote full cross-linking of the colloidal material and form a stable interfacial bonding layer while avoiding oxidation of the metal interface. The curing time of 30-45 minutes refers to the processing time required for the colloidal material to transform from a liquid to a solid state. This can be achieved using a timer control device. Its purpose is to ensure complete curing of the colloidal material while maintaining production efficiency, preventing insufficient interfacial bonding due to too short a time or increased energy consumption due to too long a time.

[0063] Specifically, after the silver-nickel alloy layer of the copper-based busbar and the ceramic insulating layer of the aluminum-based busbar form a mechanical interlocking structure, a thermally and electrically conductive adhesive is uniformly coated on the connection interface. During the curing process, the adhesive penetrates into the rough surface gaps of the silver-nickel alloy layer and the pores of the ceramic insulating layer, forming a continuous conductive network and anchoring structure after curing. The curing temperature is controlled within the range of 80-100℃ to ensure that the adhesive molecular chains are fully cross-linked to improve adhesion, while avoiding excessive temperature that could lead to oxidation of the silver-nickel alloy layer or cracking of the ceramic layer. The curing time of 30-45 minutes allows the adhesive to form chemical bonds with the metal interface while completing the cross-linking reaction, thus combining the advantages of mechanical interlocking and adhesive bonding, achieving a significant reduction in interfacial contact resistance and a dual improvement in bonding strength.

[0064] Traditional copper-aluminum composite busbars are typically fixed using only bolt connections or laser welding. The interfacial contact resistance is easily affected by surface oxidation and assembly gaps, while simply using conductive adhesive for bonding results in conductivity degradation due to adhesive aging. This solution utilizes the synergistic effect of mechanical interlocking and adhesive filling to eliminate minute interfacial gaps and strengthen the mechanical bond through adhesive anchoring, maintaining a stable low contact resistance even under vibration and temperature fluctuation conditions.

[0065] This application effectively reduces the interfacial contact resistance of the copper-aluminum composite busbar, prevents local temperature rise and oxidation aggravation under high current conditions, and enhances the interfacial bonding strength, avoiding connection loosening due to vibration or thermal stress during long-term use, thereby significantly improving the conductivity stability and service life of the track socket busbar.

[0066] Example 1

[0067] The copper-based components of the busbar in this disclosure include: 99.0 wt% copper matrix, 0.8 wt% silver-nickel alloy powder, 0.05 wt% grain boundary strengthening additives, and trace impurities.

[0068] S1, Copper-based pretreatment and laser alloying: The copper-based surface is polished step by step with sandpaper to remove the oxide scale until the metallic luster is exposed; then it is ultrasonically cleaned in an ethanol solution with a power of 400W for 12 minutes to ensure that the residual oil on the surface is ≤0.01g / m². Surface alloying was performed using a green laser with the following process parameters: power 700W, scanning speed 8mm / s, spot diameter 0.5mm, and energy density 25J / cm². A mixture of silver-nickel alloy powder and grain boundary strengthening additives was fused onto the copper substrate to form a 15μm thick silver-nickel alloy layer with a surface roughness Ra of 1.8μm, forming a 3-5μm deep metallurgical bonding layer with the copper substrate. The laser-treated copper substrate was immersed in a 6 g / L sodium chromate solution and passivated at room temperature for 10 min to form a dense oxide film with a thickness of 0.5 μm on the surface of the alloy layer.

[0069] S2. Aluminum-based pretreatment and micro-arc oxidation: The aluminum substrate is first degreased with an alkaline solution, and then activated by acid washing with a 12% HNO3 solution. After treatment, the surface contact angle is ≤30°. The alkaline degreasing uses an 8g / L NaOH solution at a temperature of 55℃ for 6 minutes, and the acid washing is carried out at room temperature for 6 minutes. A stepped voltage control is adopted, first pre-oxidizing at 300V for 5s, then increasing to 450V for main oxidation for 15min. Auxiliary parameters: frequency 800Hz, duty cycle 10%. Nano-SiO2 particles in the electrolyte are embedded in the ceramic layer to form a composite ceramic layer with a thickness of 20μm, containing 6wt% SiO2. The ceramic layer is sealed in boiling water at 98℃ for 30 minutes to ensure that the water absorption rate is ≤0.1%.

[0070] S3. Composite Assembly and Performance Control: The copper-based and aluminum-based layers are joined by laser welding at a power of 1200W and a welding speed of 2mm / s. The rough surface of the silver-nickel alloy layer and the porous structure of the ceramic layer form a microscopic interlock. A thermally and electrically conductive adhesive with a thickness of 8μm is applied to the interlocking interface and cured using a gradient temperature increase method. The first temperature is 80℃ for 15 minutes, and the second temperature is 100℃ for 25 minutes. After stress release treatment at 120℃ for 30 minutes, and with the help of precision straightening fixtures, the overall flatness of the composite busbar is ensured to be ≤0.1mm / m.

[0071] Example 2 The difference from Example 1 is that the grain boundary strengthening additive, namely trimethyl borate, was omitted.

[0072] Example 3 The difference from Example 1 is that the ratio of silver-nickel alloy powder is 6:4.

[0073] Example 4 The difference from Example 1 is that in step S1, copper-based pretreatment and laser alloying: the copper-based surface is polished step by step with sandpaper to remove the oxide scale until the metal luster is exposed; then it is placed in an ethanol solution for ultrasonic cleaning at a power of 400W for 12 minutes to ensure that the residual oil on the surface is ≤0.01g / m². Surface alloying was performed using a green laser with the following process parameters: power 700W, scanning speed 8mm / s, spot diameter 0.5mm, and energy density 25J / cm². A mixture of silver-nickel alloy powder and grain boundary strengthening additives was fused onto the copper substrate to form a 15μm thick silver-nickel alloy layer with a surface roughness Ra of 1.8μm, forming a 3-5μm deep metallurgical bonding layer with the copper substrate.

[0074] Example 5 The difference from Example 1 is that the micro-arc oxidation electrolyte removes sodium silicate, i.e., the ceramic layer does not contain SiO2.

[0075] Example 6 The difference from Example 1 is that fixed parameters are used in step S2: frequency 800Hz, duty cycle 10% stepless voltage.

[0076] Example 7 The difference from Example 1 is that no thermally conductive and electrically conductive adhesive is applied in step S3.

[0077] Comparative analysis of the performance degradation in Examples 1-7 demonstrates that grain boundary strengthening additives, silver-nickel ratio, chemical passivation, SiO2 doped ceramic layer, stepped voltage micro-arc oxidation, interface conductive adhesive reinforcement, and copper-aluminum thickness ratio are all core essential features. The absence of any one of these features will result in a 3%-4% decrease in conductivity, a 20%-30% reduction in salt spray resistance time, or a more than 3-fold deterioration in flatness.

[0078] like Figure 3 As shown, this application further proposes a track socket composite busbar 3, including a copper base 31 and an aluminum base 32. The surface of the copper base 31 is provided with a silver-nickel alloy layer and the two are metallurgically bonded. The surface of the aluminum base 32 is provided with a ceramic insulation layer and the two are bonded in situ. The copper base 31 and the aluminum base 32 are fixed by bolts, clips or laser welding. The silver-nickel alloy layer and the ceramic insulation layer form a mechanical interlocking interface.

[0079] Metallurgical bonding refers to the atomic-level bonding between a silver-nickel alloy layer and a copper substrate achieved through laser cladding. Specifically, this can be achieved by using a green laser to clad silver-nickel alloy powder, eliminating the risk of coating peeling. In-situ bonding refers to the direct formation of a ceramic insulating layer on the aluminum substrate surface during micro-arc oxidation. This can be achieved by controlling the electrolyte reaction with a stepped voltage, avoiding thermal expansion mismatch between dissimilar materials. Mechanical interlocking refers to the microscopic interlocking formed between the rough surface morphology of the silver-nickel alloy layer and the porous structure of the ceramic insulating layer. This can be achieved by controlling the laser cladding roughness and the micro-arc oxidation porosity, enhancing the interface's shear resistance.

[0080] Specifically, the silver-nickel alloy layer on the surface of the copper substrate 31 forms a continuous crystal structure through metallurgical bonding, providing oxidation protection while maintaining high conductivity. The ceramic insulating layer on the surface of the aluminum substrate 32 forms a chemical bond through in-situ bonding, improving environmental corrosion resistance while achieving insulation performance. The copper and aluminum substrates are macroscopically fixed by bolts, clips, or laser welding, while the mechanical interlocking interface between the silver-nickel alloy layer and the ceramic insulating layer creates a microscopic interlocking, forming a three-level reinforcement mechanism of macroscopic fixation, microscopic interlocking, and atomic-level bonding. This synergistic effect effectively suppresses interface delamination while simultaneously meeting the requirements for conductivity and insulation.

[0081] Traditional copper-aluminum composite busbars often employ a single bonding method, such as bolt fastening or welding, which results in delamination due to insufficient interfacial bonding strength. This solution optimizes the surface properties of both the copper and aluminum substrates through metallurgical bonding and in-situ bonding, respectively. Furthermore, a multi-level reinforced structure is formed at the interface through mechanical interlocking, significantly improving interfacial stability while maintaining conductivity and insulation properties. In existing technologies, aluminum substrate surfaces typically use sprayed insulating layers, which exhibit poor bonding strength and temperature resistance. In contrast, the micro-arc oxidation ceramic layer in this solution achieves higher bonding strength through in-situ growth.

[0082] This application solves the delamination failure problem caused by insufficient interfacial bonding strength in copper-aluminum composite busbars, while simultaneously achieving a synergistic improvement in conductivity and corrosion resistance. The metallurgical bonding of the silver-nickel alloy layer ensures the long-term conductivity stability of the copper base, the in-situ bonding of the ceramic insulation layer provides reliable insulation protection, and the mechanical interlocking interface effectively suppresses interfacial displacement caused by vibration and thermal cycling. This composite structure maintains low contact resistance and high mechanical strength under complex operating conditions, extending the service life of the busbar in humid and high-load environments.

[0083] This application further proposes that the thickness of the copper base 31 is 0.8-1.5 mm, the thickness of the aluminum base 32 is 1.2-2.0 mm, the thickness deviation of the silver-nickel alloy layer is controlled within ±2 μm, the thickness deviation of the ceramic insulation layer is controlled within ±3 μm, and the overall flatness of the composite busbar 3 is limited to within 0.1 mm / m.

[0084] The thickness range of the copper substrate 31 refers to the balance between conductivity and mechanical strength of the copper-based material. This can be achieved through rolling combined with annealing. This thickness range meets current-carrying requirements while avoiding the risk of mechanical deformation due to excessive thinness. The thickness range of the aluminum substrate 32 refers to the optimized design of the aluminum-based material between structural support and thermal stress balance. This can be achieved through extrusion molding combined with surface treatment. This thickness range can offset the interfacial stress caused by the difference in thermal expansion between copper and aluminum. Thickness deviation control of the silver-nickel alloy layer refers to achieving coating uniformity through optimization of laser cladding process parameters. Specifically, a closed-loop feedback system can be used to adjust the laser power and scanning speed in real time. This control precision ensures the uniformity of mechanical bonding between the alloy layer and the ceramic layer. Thickness deviation control of the ceramic insulating layer refers to achieving film consistency through coordinated adjustment of electrolyte concentration and voltage during the micro-arc oxidation process. Specifically, a constant current pulse power supply combined with temperature monitoring can be used. This control precision maintains the interlocking effectiveness of the porous structure. Overall flatness limitation refers to the deformation control index after the composite busbar 3 is assembled. Specifically, it can be achieved through composite interface stress analysis and assembly tooling optimization. This index can ensure the fit between the busbar and the socket housing.

[0085] Specifically, the thickness ratio of the copper-based and aluminum-based materials is balanced by a stiffness-matching principle to offset differences in thermal expansion. When the copper-based layer is thinner, the aluminum-based layer is appropriately thickened to provide reverse stiffness and suppress warping caused by temperature changes. Thickness deviations between the silver-nickel alloy layer and the ceramic insulation layer are controlled through precision machining. The rough surface of the alloy layer complements the porous structure of the ceramic layer; excessive deviation can lead to localized interlocking failure or stress concentration. Overall flatness is maintained through stress release and straightening processes after composite assembly, ensuring uniform heat dissipation and stable installation at the contact surfaces of the busbar and socket housing.

[0086] In some specific implementations, the thickness ratio of the copper-based to the aluminum-based layer can be dynamically adjusted according to the current level. For example, a thin combination of 0.8mm copper-based and 1.2mm aluminum-based layer is used in low-current scenarios, while a thick combination of 1.5mm copper-based and 2.0mm aluminum-based layer is used in high-current scenarios. The thickness control of the silver-nickel alloy layer and the ceramic insulating layer can be monitored in real time by online detection equipment, such as using a laser thickness gauge and an optical profilometer to adjust process parameters in a linked feedback manner.

[0087] Traditional composite busbar design uses fixed copper and aluminum thicknesses, failing to consider flatness degradation caused by differences in thermal expansion coefficients, and lacks sufficient precision in controlling surface layer thickness deviation, resulting in a high risk of interface bonding failure. This solution systematically solves the problems of thermal stress balance and interface bonding quality through dynamic copper-aluminum thickness ratio and high-precision surface layer control.

[0088] This application effectively avoids warping and deformation of the composite busbar 3 due to thickness mismatch, ensuring a tight fit with the socket housing during installation and reducing contact resistance fluctuations and uneven heat dissipation. Strict control of surface layer thickness deviation maximizes the contact area of ​​the mechanical interlocking interface, reducing the risk of localized overheating and stress cracking, and improving the long-term stability and reliability of the busbar.

[0089] Example 9 like Figures 2-3 As shown, this application further proposes a track socket, including a composite busbar 3, which is disposed in the conductive channel 2 of the socket and connected at both ends to the input terminal and the output terminal of the socket, respectively; the socket also includes an insulating shell, and the insulating shell is provided with heat dissipation holes corresponding to the position of the composite busbar 3.

[0090] The composite busbar 3 refers to a conductive device formed by metallurgically bonding copper and aluminum substrates. The copper substrate is covered with a silver-nickel alloy layer, and the aluminum substrate is covered with a ceramic insulating layer. The mechanical interlocking interface achieves a synergistic effect of conductivity and insulation. Specifically, the copper and aluminum substrates can be fixed using laser welding or bolt connections, thereby reducing interfacial contact resistance and improving structural stability. The heat dissipation holes are through-holes on the surface of the insulating shell corresponding to the positions of the composite busbar 3. These can be implemented using an array arrangement or directional opening method, accelerating heat dissipation from the busbar surface through air convection and preventing excessive local temperature rise that could degrade material performance. The input and output terminals are conductive interfaces located at both ends of the socket, specifically using copper alloy terminals or silver-plated terminals. They are connected to the composite busbar 3 via bolt crimping or welding to form a complete conductive path.

[0091] Specifically, the composite busbar 3 is integrated within the conductive channel 2. The copper-based portion performs the main conductive function, while the aluminum-based portion achieves electrical isolation through a ceramic insulating layer. Both ends of the composite busbar 3 are connected to the input and output terminals, forming a low-resistance current path. The insulating shell covers the composite busbar 3 and has corresponding ventilation holes to dissipate heat generated during operation via air convection. The ventilation holes are precisely positioned to correspond to the heat-generating areas of the busbar, avoiding localized heat accumulation caused by misaligned openings in traditional heat dissipation designs. The copper-aluminum composite structure reduces contact resistance and Joule heating through a metallurgical interface, while the ceramic insulating layer isolates the risk of leakage without compromising heat dissipation efficiency.

[0092] Traditional rail socket designs typically involve evenly spaced ventilation holes on the casing surface, neglecting the actual heat-generating locations of the busbars. This results in low heat dissipation efficiency and compromises casing insulation strength. This solution addresses this by aligning the ventilation holes with the heat-generating areas of the composite busbar 3, achieving directional heat dissipation and improving efficiency while maintaining overall casing insulation. Furthermore, existing busbars are often made of a single metal material, making it difficult to balance conductivity and heat dissipation requirements. The composite busbar 3, through a copper-aluminum synergistic design, reduces resistance while leveraging the lightweight properties of aluminum to enhance heat dissipation.

[0093] This application effectively solves the problem of conductivity degradation caused by temperature rise during long-term use of the composite busbar 3. It accelerates heat dissipation through directional heat dissipation holes, preventing the insulating shell from aging due to localized overheating. The copper-aluminum composite structure of the composite busbar 3 reduces contact resistance and heat generation, forming a synergistic heat dissipation mechanism with the heat dissipation holes, ensuring reliable connection and long-term stable operation of the conductive channel 2. While achieving electrical isolation, the insulating shell maintains overall mechanical strength through precise perforations, preventing the heat dissipation structure from weakening its protective performance.

[0094] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for manufacturing a track socket busbar, characterized in that, The copper-based components of the busbar include: The manufacturing method comprises 98.5–99.5 wt% copper matrix, 0.4–1.2 wt% silver-nickel alloy powder, and 0.03–0.06 wt% grain boundary strengthening additives. The core process steps are described below, and each step synergistically improves both electrical conductivity and corrosion resistance: S1. First, polish the surface of the copper-based busbar to remove the oxide scale, and then use ethanol ultrasonic cleaning to remove the oil stains. Subsequently, a green laser is used for surface alloying, and the silver-nickel alloy powder is fused onto the surface of the copper-based busbar to form a silver-nickel alloy layer with a thickness of 10-20 μm that is bonded to the copper-based metallurgy. The surface roughness Ra of the silver-nickel alloy layer is 1.5-2.0 μm. S2, the aluminum-based busbar is subjected to alkaline degreasing and acid pickling activation in sequence; Subsequently, micro-arc oxidation is carried out in an electrolyte containing 15-20 g / L sodium silicate, 2-5 g / L potassium hydroxide, and 3-6 g / L sodium fluoride, using a stepped voltage control to generate a ceramic insulating layer that bonds in situ with the aluminum substrate; finally, the pores are sealed by boiling water impregnation to ensure that the water absorption rate of the ceramic insulating layer is ≤0.1%. S3, the copper-based busbar treated by S1 and the aluminum-based busbar treated by S2 are combined and fixed by bolt connection, snap connection or laser welding. The silver-nickel alloy layer of the copper-based busbar and the ceramic insulation layer of the aluminum-based busbar form a mechanical interlocking structure. The mechanical interlocking structure is formed by the predetermined roughness of the silver-nickel alloy layer and the porous growth morphology of the ceramic insulation layer, and finally a composite busbar is obtained.

2. The manufacturing method according to claim 1, characterized in that, The grain boundary strengthening additive is trimethyl borate or triethyl phosphate, which is mixed evenly with silver-nickel alloy powder before laser surface alloying. The additive decomposes to generate active elements during the laser cladding process, which react with oxygen and sulfur impurities at the copper-based grain boundaries, so that the content of copper-based grain boundary impurities is ≤10ppm.

3. The manufacturing method according to claim 1, characterized in that, The silver-nickel alloy powder described in S1 has a silver-nickel mass ratio of 7:3 to 9:1, and the laser process parameters are as follows: Power 600-800W, scanning speed 5-10mm / s, spot diameter 0.4-0.6mm, energy density 15-35J / cm².

4. The manufacturing method according to claim 3, characterized in that, After laser surface alloying in S1, chemical passivation treatment is also included: the silver-nickel alloy layer is immersed in a chromate solution to form a passivation film with a thickness of 0.5-1.0 μm on its surface. The passivation film increases the salt spray resistance time of the silver-nickel alloy layer by 20-30%.

5. The manufacturing method according to claim 1, characterized in that, The ceramic insulating layer of S2 with micro-arc oxidation has a thickness of 15-25μm, a hardness of 1000-2000HV, and an insulation resistance of ≥100MΩ. The ceramic insulating layer is mainly composed of Al2O3 and contains 5-8wt% SiO2 to reduce the internal stress of the film.

6. The manufacturing method according to claim 5, characterized in that, S2 also includes micro-arc oxidation auxiliary parameters for cooperating with the stepped voltage control, wherein the micro-arc oxidation auxiliary parameters are a frequency of 500-1000Hz, a duty cycle of 8-12%, and an oxidation time of 8-20min.

7. The manufacturing method according to claim 1, characterized in that, The composite assembly in S3 also includes an interface reinforcement step: Apply thermally and electrically conductive adhesive to the interface between the copper-based and aluminum-based components, and then cure at 80-100℃ for 30-45 minutes to ensure that the interfacial contact resistance of the composite busbar is ≤5×10⁻⁶. -6 Ω・cm.

8. A composite busbar for a track socket, characterized in that, The composite busbar is manufactured using the manufacturing method according to any one of claims 1-7, and comprises: A copper substrate with a silver-nickel alloy layer on its surface, wherein the silver-nickel alloy layer is metallurgically bonded to the copper substrate. An aluminum substrate with a ceramic insulating layer on its surface, wherein the ceramic insulating layer is bonded to the aluminum substrate in situ. The copper base and the aluminum base are fixed by bolts, clips or laser welding, and the silver-nickel alloy layer and the ceramic insulating layer form a mechanical interlocking interface.

9. The composite busbar for the track socket according to claim 8, characterized in that, The thickness of the copper base is 0.8-1.5mm, the thickness of the aluminum base is 1.2-2.0mm, the thickness deviation of the silver-nickel alloy layer is ≤±2μm, and the thickness deviation of the ceramic insulation layer is ≤±3μm, ensuring that the overall flatness of the composite busbar is ≤0.1mm / m.

10. A track socket, characterized in that, The socket includes the composite busbar as described in claim 8 or 9, wherein the composite busbar is disposed within the conductive channel of the socket and its two ends are respectively connected to the input terminal and the output terminal of the socket; the socket also includes an insulating housing, wherein the insulating housing is provided with heat dissipation holes corresponding to the position of the composite busbar.

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