Aluminum-plated alloy copper transition joint of aluminum cable and preparation method of aluminum-plated alloy copper transition joint

Abstract

The invention discloses an aluminum-plated alloy copper transition joint of an aluminum cable. The aluminum-plated alloy copper transition joint comprises an aluminum cable; the aluminum alloy-plated copper transition terminal is wrapped at the tail end of the aluminum cable to form an aluminum cable plug part; the aluminum-plated alloy copper transition terminal comprises a terminal base body made of copper. And an aluminum alloy coating is arranged on the terminal base body on one side of the aluminum alloy-plated copper transition terminal, which is in contact with the aluminum cable. The aluminum-plated alloy copper transition joint of the aluminum cable has excellent corrosion resistance and short-time current resistance, and the problems that an existing copper-aluminum cable transition joint is poor in corrosion resistance and safety can be solved.

Description

Technical Field

[0001] The present invention relates to the field of electric power technology, and particularly relates to an aluminum alloy-plated copper transition joint for aluminum cables and a preparation method thereof. Background Art

[0002] Compared with copper alloy cables, the cost of aluminum alloy cables can be reduced by 20% - 40%, and the weight can be reduced by 3.3 times. They have the advantages of low cost, easy processing, convenient installation, and good transmission performance. At the same time, with the continuous exploration of aluminum-copper technology, the safety current-carrying capacity, conductivity, safety, conductor resistivity, and current-carrying capacity of current aluminum alloy cables can be completely equivalent to those of traditional copper cables. However, since the AC switches and AC terminal blocks in inverters and power distribution cabinets are all made of copper, when conductors of copper and aluminum materials are directly connected, on the one hand, due to the differences in elastic modulus and thermal expansion coefficient between copper and aluminum, after multiple cold and hot cycles (power on and power off), large gaps will be generated at the contact points, resulting in poor contact. On the other hand, the electrode potential of aluminum (-1.66V) is relatively low, and it is easy to lose electrons and become the negative electrode. The standard electrode potential of copper is high (+0.337 - +0.521), and it is difficult to lose electrons and become the positive electrode. When combined with water and CO2 in the air, an electrochemical primary battery structure will be formed, resulting in the gradual electrochemical corrosion of the aluminum material, a rapid decrease in mechanical strength and electrical conductivity, an increase in the contact resistance between copper and aluminum, and poor contact. Especially when current passes through, the increase in temperature will accelerate the corrosion, and even cause accidents such as smoking and burning.

[0003] Currently, methods such as copper-aluminum transition connecting pipes, metal pins, and secondary zinc immersion are often used to solve the problem of direct connection of copper-aluminum cables. Among them, both the copper-aluminum transition connecting pipe and the metal pin method use the method of welding the copper-aluminum contact surface to achieve the connection of copper wire and aluminum wire in the longitudinal distribution of copper material and aluminum material. Due to process reasons, they are often unable to be miniaturized, there is more material loss during the operation process, and the welds are prone to corrosion and fracture after being exposed to moisture. The secondary zinc immersion method is a method in which the insulating wrapping layer of the wire is first stripped by 15 - 25 mm with an aluminum wire pliers, the aluminum wire head is pre-tinned, and then connected to the copper cable. This method has complex operations and high requirements for personnel operation. Moreover, in the actual operation process, an ordinary soldering iron is generally used directly for tinning, and the tin layer is easily peeled off in a short time. After the copper-aluminum contact is exposed to moisture, an electrochemical reaction will occur, causing the cable to burn out. Therefore, there is an urgent need to provide a transition terminal with high safety when connecting to aluminum wires and convenient preparation. Summary of the Invention

[0004] In order to overcome the problems of poor corrosion resistance and poor safety of the copper-aluminum cable transition joint in the prior art, the present invention proposes an aluminum alloy-plated copper transition joint for aluminum cables and a preparation method thereof. The above object is achieved through the following implementation manners of technical solutions:

[0005] An aluminum alloy-plated copper transition joint for aluminum cables, comprising:

[0006] Aluminum cable

[0007] An aluminum alloy - plated copper transition terminal, which is wrapped around the end of the aluminum cable to form an aluminum cable plug - in part

[0008] The aluminum alloy - plated copper transition terminal includes a terminal base made of copper; an aluminum alloy coating is provided on the terminal base on the side where the aluminum alloy - plated copper transition terminal contacts the aluminum cable

[0009] Optionally, an aluminum cable socket part is provided on the surface of the terminal base away from the aluminum cable, and the aluminum cable socket part is made of copper

[0010] Preferably, the socket part is cylindrical, and one end bottom surface of the aluminum cable socket part is fixed at the end of the aluminum cable plug - in part

[0011] Preferably, the end of the aluminum cable plug - in part has an opening; the aluminum cable passes through the opening and enters the inside of the aluminum cable socket part and contacts the inner wall of the aluminum cable socket part

[0012] Preferably, an aluminum alloy coating is provided on the outer surface of the aluminum cable socket part

[0013] Preferably, the aluminum cable is a pure aluminum cable or an aluminum alloy cable

[0014] Optionally, the aluminum alloy coating is an aluminum alloy containing gadolinium; the mass fraction of gadolinium in the aluminum alloy coating is 0.15 - 0.35%

[0015] A connecting device for an aluminum cable and a copper cable, comprising:

[0016] The above - mentioned aluminum alloy - plated copper transition joint of the aluminum cable, which does not have an aluminum cable socket part; and

[0017] A copper cable socket that mates with the aluminum cable plug - in part; the copper cable socket is made of copper; the copper cable socket is connected to the copper cable

[0018] The aluminum alloy - plated copper transition joint is inserted into the copper cable socket

[0019] Preferably, an epoxy resin layer is coated at the interface between the aluminum alloy - plated copper transition joint and the copper cable socket

[0020] A connecting device for an aluminum cable and a copper cable, comprising:

[0021] The above - mentioned aluminum alloy - plated copper transition joint of the aluminum cable, and it has an aluminum cable socket part; and

[0022] A copper cable plug that mates with the aluminum cable socket portion; the copper cable plug is made of copper; the copper cable plug is connected to a copper cable;

[0023] The copper cable plug is inserted into the aluminum cable socket portion of the aluminum alloy-plated copper transition joint;

[0024] Preferably, an epoxy resin layer is coated at the interface between the copper cable plug and the aluminum cable socket portion of the aluminum alloy-plated copper transition joint.

[0025] A connecting device for aluminum cables, comprising:

[0026] A first joint, including the aluminum alloy-plated copper transition joint of the above-mentioned aluminum cable;

[0027] A second joint, including the aluminum alloy-plated copper transition joint of the above-mentioned aluminum cable, and a terminal base on the side of the aluminum alloy-plated copper transition terminal away from the aluminum cable is provided with an aluminum cable socket portion.

[0028] The preparation method of the aluminum alloy-plated copper transition joint of the above-mentioned aluminum cable includes the following steps:

[0029] Step 1) Prepare an aluminum alloy coating on one side of a copper strip by molten salt electroplating; obtain a copper strip plated with aluminum alloy;

[0030] Step 2) Process the aluminum alloy-coated copper strip to form the aluminum alloy-plated copper transition terminal; and make the aluminum alloy coating located on the inner surface of the aluminum alloy-plated copper transition terminal;

[0031] Step 3) Install the aluminum alloy-plated copper transition terminal at the end of the aluminum cable.

[0032] Optionally, the method of preparing an aluminum alloy coating on one side of a copper strip by molten salt electroplating includes:

[0033] 1) Clean the copper strip; and cover a masking material on one side surface of the copper strip;

[0034] 2) Perform surface treatment on the aluminum anode;

[0035] 3) Heat a mixed salt containing AlCl3, NaCl, KCl and gadolinium to melting to form a molten salt;

[0036] 4) Use the copper strip as the cathode and insert it into the molten salt together with the aluminum anode for electroplating treatment; the electroplating temperature is 450 - 520K, and the current density is 16 - 24 mA / cm 2 , and the electroplating time is 8 - 25 min;

[0037] 5) Remove the masking material after electroplating is completed.

[0038] Optionally, the cleaning of the copper strip includes alkaline cleaning and acid cleaning carried out in sequence;

[0039] Preferably, the molar ratio of AlCl3:NaCl:KCl is 4:1:1 to 8:1:1, and the gadolinium content in the molten salt is 0.15 to 0.35%;

[0040] Preferably, the thickness of the copper strip is 1 to 20 mm, and the thickness of the aluminum alloy coating is 10 to 26 μm.

[0041] Optionally, the preparation method further includes step (iii), using the copper strip plated with aluminum alloy to form an aluminum cable socket part on the copper-aluminum alloy plated transition terminal, and making the aluminum alloy coating located on the outer surface of the aluminum cable socket part.

[0042] The present invention has the following beneficial effects:

[0043] Based on the most commonly used tin-plated copper terminals connected to the DC side (copper cable end) of the market-end components, the present invention designs two types of copper-aluminum alloy plated transition joints for aluminum cables, which can be used for the connection of copper-aluminum cables. The copper-aluminum alloy plated transition joint for aluminum cables of the present invention has excellent corrosion resistance and short-time withstand current performance, and can overcome the problems of poor corrosion resistance and poor safety of the existing copper-aluminum cable transition joints.

[0044] Considering that it is expected to replace the copper cable on the DC side with an aluminum cable in the future to reduce costs, the present invention also provides a wiring terminal for the connection of aluminum-aluminum cables, which can be used for the connection of equipment such as the DC side and the inverter and distribution box ends.

[0045] The aluminum alloy of the present invention is prepared by doping rare earth metal gadolinium in aluminum. Gadolinium has the functions of refining and homogenizing aluminum grains, increasing the corrosion resistance and hardness of the coating. The wiring terminal of the present invention is composed of two cylindrical aluminum alloy copper strips welded together, one with an aluminum alloy inner layer and a copper outer layer, and the other with a copper inner layer and an aluminum alloy outer layer. The two cylindrical aluminum alloy copper strips are prepared by taking a copper strip as a substrate, electroplating an aluminum alloy film, and then curling the copper strip inward and outward respectively. At the same time, a layer of epoxy resin is evenly coated on the outer surface of the metal to enhance the sealing performance of the material and improve the antioxidant and anti-electroerosion properties of the metal material. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0047] Figure 1It is a schematic diagram of Embodiment 1;

[0048] Figure 2 It is a schematic diagram of the internal structure of Embodiment 1;

[0049] Figure 3 It is a schematic diagram of the connection between Embodiment 1 and a copper cable;

[0050] Figure 4 It is a schematic diagram of Embodiment 2;

[0051] Figure 5 It is a schematic diagram of the internal structure of Embodiment 2;

[0052] Figure 6 It is a schematic diagram of the connection between Embodiment 2 and a copper cable;

[0053] Figure 7 It is a schematic diagram of the connection between two aluminum cables in Embodiment 3;

[0054] Figure 8 It is a plating flow chart;

[0055] Figure 9 It is a schematic diagram of terminal preparation. Detailed implementation manners

[0056] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention. It should be understood that the terms described in the present invention are only used to describe specific implementation manners and are not used to limit the present invention.

[0057] In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0058] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention.

[0059] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0060] Embodiment 1:

[0061] As Figure 1, 2 As shown in the figure, this embodiment provides an aluminum alloy-plated copper transition joint for aluminum cables, including an aluminum alloy-plated copper transition terminal 2, which is used to wrap the end of the aluminum cable 1 to form an aluminum cable plug head.

[0062] The aluminum alloy-plated copper transition terminal is cylindrical and includes a terminal matrix 21 made of copper; an aluminum alloy coating 22 is provided on the terminal matrix on the side where the aluminum alloy-plated copper transition terminal contacts the aluminum cable 1. The aluminum alloy coating is an aluminum alloy containing gadolinium; the gadolinium content in the aluminum alloy coating is 0.2%.

[0063] Based on the above-mentioned aluminum alloy-plated copper transition terminal, an aluminum cable joint can be made. Use a wire stripper to strip the cable to expose the aluminum core. After inserting the aluminum core into the cylindrical terminal, use a crimping tool to crimp and seal it to form an aluminum cable plug head, as Figure 1 shown. The end of the plug head is open, and the end of the aluminum cable is located inside the terminal. To cooperate with the connection of commonly used tin-plated copper connectors in the industry, the size of the aluminum alloy-plated copper wiring terminal is not particularly limited. This transition terminal is not limited to being circular and can also be processed into various shapes to facilitate the connection of copper-aluminum wires of various shapes such as circular, polygonal, and elliptical for application in various installation environments.

[0064] This embodiment also provides a connection device for an aluminum cable and a copper cable. As Figure 3 shown, the connection of the aluminum cable and the copper cable 4 is designed based on the most commonly used tin-plated copper terminal at the DC side (copper cable end) of the market-end component. The aluminum cable plug head of the aluminum alloy-plated copper transition joint of the aluminum cable obtained in this embodiment is inserted into the copper cable socket part 5 made of tin-plated copper at the copper cable end to achieve the connection.

[0065] As Figure 3 shown, in the formed connection structure, the aluminum cable only contacts the aluminum alloy coating, and the copper cable socket part of the copper cable only contacts the copper layer of the terminal, ensuring that the inner layer at the end of the terminal and the contact part of the cable, as well as the connection part of the two terminals, belong to the same material to avoid direct contact between different materials and exposure to the air to cause electrochemical corrosion. At the same time, in order to prevent the ingress of moisture in the air from causing electrochemical corrosion, a layer of aging-resistant black epoxy resin layer needs to be evenly coated on the outside of the terminal and the welding part to improve the antioxidant and anti-electroerosion properties of the material.

[0066] Embodiment 2:

[0067] This embodiment provides another aluminum alloy-plated copper transition joint for aluminum cables. As Figure 4 , 5As shown, based on the aluminum cable plug head formed in Embodiment 1, in this embodiment, an aluminum cable socket part 3 is further provided on the surface of the terminal base away from the aluminum cable; the aluminum cable socket part 3 is cylindrical, the base body 31 of the aluminum cable socket part is made of copper, and the bottom surface of the aluminum cable socket part is fixed at the end of the aluminum cable plug head. An aluminum alloy coating 32 is provided on the outer surface of the base body 31 of the aluminum cable socket part; the aluminum alloy coating is an aluminum alloy containing gadolinium; the gadolinium content in the aluminum alloy coating is 0.2%.

[0068] As Figure 5 shown, in this embodiment, the end of the aluminum cable plug head 2 is open, and the end of the aluminum cable 1 passes through the opening and enters the inside of the aluminum cable socket part 3 and contacts the copper inner wall of the aluminum cable socket part 3. This structure ensures close contact between the aluminum cable and the aluminum cable socket part. When the transition joint is in use, the inside of the aluminum cable socket part is completely enclosed, isolating the external environment, and can also ensure that electrochemical corrosion does not occur between the end of the aluminum cable and the inner wall of the aluminum cable socket part.

[0069] As Figure 6 shown, this kind of aluminum cable socket part structure is used to cooperate with the copper cable plug 6 made of tinned copper of the copper cable 4. The copper cable plug 6 made of tinned copper of the copper cable is inserted into the aluminum cable socket part 3 of this embodiment. In the formed connection structure, the copper cable plug 6 made of tinned copper only contacts the copper layer of the aluminum cable socket part 3. Since the two terminal plug-in connections belong to the same material, direct contact between different materials can be avoided, and electrochemical corrosion caused by exposure to the air can be prevented. At the same time, in order to prevent the ingress of moisture in the air from causing electrochemical corrosion, a layer of aging-resistant black epoxy resin layer needs to be evenly coated on the outside of the terminal and the welding place to improve the antioxidant and anti-electroerosion properties of the material.

[0070] Embodiment 3

[0071] In this embodiment, considering that it is expected to replace the copper cable on the DC side with an aluminum cable in the future, as Figure 7 shown, by combining the two aluminum cable terminals in Embodiment 1 and Embodiment 2, the connection of aluminum-aluminum cables can be achieved. In this way, the plug-in connection parts of the two wiring terminals are both made of copper, and the inner layer at the end is made of aluminum at the connection with the aluminum cable.

[0072] It should be noted that the above-mentioned aluminum cable includes both cables made of pure aluminum and aluminum alloy cables commonly used in the prior art.

[0073] Embodiment 4

[0074] This embodiment discloses a preparation method of the above-mentioned transition terminal:

[0075] Electroplating technology is a process that uses electrolysis to deposit a metal or alloy film on the surface of a substrate. It not only has simple equipment, low cost, and easy operation, but also can form a dense and uniform coating on the surface of the base metal. However, due to the standard electrode potential of aluminum (-1.66V) being much more negative than that of hydrogen (0V), it is impossible to prepare an aluminum-coated layer by conventional electroplating methods, and aluminum electrodeposition can only be achieved in non-aqueous solutions. Molten salt electroplating is a technology that uses inorganic or organic salts as electrolytes to deposit a metal film with good adhesion on the substrate through electrolysis. Compared with traditional electroplating methods, the coating prepared by molten salt electroplating has stronger bonding ability, better uniformity, does not require high-temperature operation, and can better control the performance of the coating.

[0076] The present invention uses a simple, economical, and easy-to-operate molten electroplating method to prepare an aluminum alloy coating on the surface of a copper strip for the processing of copper-aluminum transition terminals. The specific process flow is as Figure 8 shown and includes the following steps:

[0077] 1. Pretreatment of the cathode material (copper strip):

[0078] (1) Alkaline cleaning of the copper strip: In this step, by adding an alkali and the surfactant sodium silicate to react with saponifiable oil and non-saponifiable oil to form soap and emulsion, the purpose of removing the oil stain on the surface of the copper strip is achieved. The formulation of the alkaline cleaning has no strict limitation, but the content of the alkali should not be too low or too high. Too low a content will result in low efficiency and poor degreasing effect, and too high a content will cause the soap formed to react with calcium, magnesium, etc. in the water to form insoluble calcium soap and magnesium soap, which will deposit on the surface of the copper sheet and be difficult to wash off with water. During subsequent pickling, it will be neutralized by the acid to form an oil film of fatty acid, resulting in poor pickling effect. The alkaline cleaning process is as follows: Put the copper strip into a mixed solution of 10g / L NaOH, 25g / L Na2CO3, 55g / L Na3PO4·12H2O, 10g / L Na2SiO3, and 2 - 3 drops of the surfactant NP-10, soak at 55 - 60°C for 25 - 30 min. Finally, wash the excess acid on the surface of the copper strip with water to remove the small amount of alkali solution and surfactant adhering to the surface of the copper strip, so as to avoid affecting the subsequent pickling effect.

[0079] (2) Pickling of the copper strip: This step is to remove the oxide film and the alkali solution remaining on the surface of the copper strip. Usually, the copper strip is put into 15g / L H2SO4 and soaked at 40 - 60°C for 1 - 3 min. Finally, wash the excess acid on the surface of the copper strip with water to keep the surface of the copper strip pure.

[0080] (3) Cover the masking material (high-temperature tape, plastic film, or coating-type masking agent) on the side that does not need to be electroplated to ensure that the masking material is closely attached to the side where aluminum electroplating is not required. In the present invention, high-temperature tape is used and torn off after electroplating to ensure that the performance of the other side is not affected.

[0081] 2. Pretreatment of the anode material (aluminum sheet):

[0082] Aluminum sheet polishing: This step is to remove the dense aluminum oxide film formed on the surface of the aluminum sheet to make electroplating easier. Select an aluminum sheet and cut it into an aluminum sheet with dimensions of 5.0 cm × 4.0 cm × 0.5 cm. Polish it with sandpaper and then rinse it with deionized water, blow it dry, and set it aside.

[0083] 3. Molten salt pretreatment:

[0084] (1) Dehydration: This step is to remove the water in the molten salt because water molecules will affect the quality of the aluminized layer. A mixed inorganic system of AlCl3 - NaCl - KCl with a molar ratio of 4:1:1 and 0.24% gadolinium is selected as the molten salt of the present invention. First, heat the inorganic system to 200 °C to completely dissolve it, and then cool it to 150 °C. Then, introduce pre-dried concentrated hydrochloric acid for dehydration.

[0085] (2) Pre-electrolytic impurity removal: This step is to remove metal impurities such as iron and chromium in the molten salt that will affect the quality of the subsequent coating. After connecting the electrolysis device to a DC regulated power supply, pass a current density of 3 - 5 mA / m 2 for 3 h at an environment of 423 K to complete impurity removal.

[0086] 4. Electroplating:

[0087] Too low electroplating temperature will affect the ion conduction rate, and too high temperature will cause the viscosity to decrease and it is not easy to form a film. The current density is the key to affecting the coating quality. If the density is too small, the plating solution will crystallize on the cathode and it is even difficult to form a coating, while too high density will burn out the molten salt. The electroplating time will also have a certain impact on the coating quality. If the time is too short, the coating will be thinner and the subsequent performance will be poor. If the time is too long, the surface of the coating will show unevenness. In the present invention, experiments are carried out under the conditions of a temperature of 473 K, a current density of 16 - 24 mA / cm 2 , and the electroplating time is 8 - 25 min. The thickness of the aluminum alloy coating obtained can reach 10 - 26 μm. After electroplating is completed, remove the above masking material to obtain a copper strip with a single-sided aluminized alloy.

[0088] 5. Preparation of copper wiring transition terminal with aluminized alloy

[0089] The specific production process of the copper transition terminal with aluminized alloy is as Figure 9 shown. This wiring transition terminal is based on a copper strip. First, use the molten salt electroplating process to stably electroplate aluminum alloy above the copper strip, as Figure 9As shown in the figure, the copper strip was curled outward and inward and welded, and two cylindrical aluminum alloy copper strips with aluminum alloy on the inner layer and copper on the outer layer, and copper on the inner layer and aluminum alloy on the outer layer were prepared respectively. Among them, the preparation method of the terminal in Example 1 was specifically as follows: the ends of the copper strip with aluminum alloy on the inner layer and copper on the outer layer were welded together by welding, that is, the terminal used in Example 1 was obtained.

[0090] The preparation method of the terminal in Example 2 was specifically as follows: on the basis of the terminal obtained in Example 1 above, the ends of the copper strip with copper on the inner layer and aluminum alloy on the outer layer were welded together to obtain an aluminum cable socket part, and the aluminum cable socket part and the aluminum cable plug part end of the terminal in Example 1 above were welded to obtain the one used in Example 2. The aluminum cable socket part accounted for about 70-90% of the aluminum alloy-plated copper wiring terminal.

[0091] In addition, the wiring terminal is not limited to a circular shape and can also be processed into various shapes to facilitate the connection of copper-aluminum wires in shapes such as circular, polygonal, and elliptical, so as to be applied to various installation environments.

[0092] Comparative Example 1

[0093] Compared with Example 1, in this comparative example, a copper terminal without an aluminum alloy coating was used to make an aluminum cable plug, and it was connected to the copper cable socket in Example 1.

[0094] Comparative Example 2

[0095] In this comparative example, a commercially available copper-aluminum transition connection pipe was used to connect the aluminum cable and the copper cable. This kind of transition connection pipe includes a copper pipe for connecting to the copper cable and an aluminum pipe for connecting to the aluminum cable; the copper pipe and the aluminum pipe are welded together.

[0096] Comparative Example 3

[0097] Compared with Example 1, in this comparative example, the gadolinium content in the aluminum alloy coating was reduced to 0.1%.

[0098] Performance Test

[0099] The above wiring terminals after pressing the cable were connected together, and then their corrosion resistance, short-time withstand current, pulling force after 120h salt spray experiment, and voltage drop were tested. The relevant standards are as follows:

[0100] Corrosion resistance: Neutral salt spray was used for evaluation. The salt spray test was carried out in accordance with the national standard "GB / T 10125 2012 Artificial Atmosphere Corrosion Test Salt Spray Test". The test temperature was 35±2°C, and the NaCl concentration was 50±5g / L. After the experiment, the time when the white rust area of the aluminum alloy-plated copper wiring terminal was >5% was recorded. It was required that the white rust area on the surface of the aluminum alloy-plated copper wiring terminal was ≤5% after 120h, otherwise the corrosion resistance was judged to be unqualified.

[0101] Short-time withstand current: Using the JB / T 2436.2-1994 standard, after the current is loaded for 1 s, observe the terminal morphology.

[0102] The judgment criteria for the voltage drop and pulling force of the terminal are: pulling force > 200 N, voltage drop ≤ 0.5 mV.

[0103] The test results are shown in Table 1:

[0104] Table 1 Performance test results

[0105]

[0106]

[0107] It can be seen from the above experimental data that the aluminum alloy-plated copper transition joint of the present invention has excellent corrosion resistance and short-time withstand current performance. It is significantly better than the uncoated pure copper joint of Comparative Example 1 and the transition connecting pipe of Comparative Example 2.

[0108] Moreover, the gadolinium-containing aluminum alloy coating of the present invention enables the transition joint to have stronger corrosion resistance. When the gadolinium content in the aluminum alloy is insufficient, the corrosion resistance will decrease.

[0109] Obviously, the above embodiments are only examples for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. An aluminum alloy-plated copper transition joint for aluminum cables, characterized in that, Comprising: Aluminum cable; Aluminum alloy plated copper transition terminal, which is wrapped around the end of the aluminum cable to form an aluminum cable plug head; The aluminum alloy plated copper transition terminal comprises a terminal base made of copper; an aluminum alloy coating is provided on the terminal base on the side where the aluminum alloy plated copper transition terminal contacts the aluminum cable.

2. The aluminum alloy-plated copper transition joint for aluminum wire and cable according to claim 1, wherein On the surface of the terminal base away from the aluminum cable, an aluminum cable socket part is provided, and the aluminum cable socket part is made of copper; Preferably, the socket part is cylindrical, and one end bottom surface of the aluminum cable socket part is fixed at the end of the aluminum cable plug head; Preferably, the end of the aluminum cable plug head has an opening; the aluminum cable passes through the opening and enters the inside of the aluminum cable socket part and contacts the inner wall of the aluminum cable socket part; Preferably, the outer surface of the aluminum cable socket part is provided with an aluminum alloy coating; Preferably, the aluminum cable is a pure aluminum cable or an aluminum alloy cable.

3. The aluminum alloy-plated copper transition joint for aluminum cables according to claim 1, characterized in that, The aluminum alloy coating is an aluminum alloy containing gadolinium; the mass fraction of gadolinium in the aluminum alloy coating is 0.15-0.35%.

4. A connecting device for an aluminum cable and a copper cable, characterized in that, Comprising: The aluminum alloy plated copper transition joint of the aluminum cable as claimed in claim 1; And A copper cable socket that mates with the aluminum cable plug head; The copper cable socket is made of copper; the copper cable socket is connected to the copper cable; The aluminum alloy plated copper transition joint is inserted into the copper cable socket; Preferably, an epoxy resin layer is coated at the interface between the aluminum alloy plated copper transition joint and the copper cable socket.

5. A connecting device for aluminum cables and copper cables, characterized in that, Comprising: The aluminum alloy plated copper transition joint of the aluminum cable as claimed in claim 2; And A copper cable plug that mates with the aluminum cable socket part; the copper cable plug is made of copper; the copper cable plug is connected to the copper cable; The copper cable plug is inserted into the inside of the aluminum cable socket part of the aluminum alloy plated copper transition joint; Preferably, an epoxy resin layer is coated at the interface between the copper cable plug and the aluminum cable socket part of the aluminum alloy plated copper transition joint.

6. An aluminum cable and a connecting device for aluminum cables, characterized in that, Comprising: A first joint, which uses the aluminum alloy plated copper transition joint of the aluminum cable as claimed in claim 1; A second joint, which comprises the aluminum alloy plated copper transition joint of the aluminum cable as claimed in claim 1, and an aluminum cable socket part is provided on the terminal base on the side of the aluminum alloy plated copper transition terminal away from the aluminum cable.

7. The preparation method of the aluminum alloy-plated copper transition joint for aluminum cables according to claim 1 or 2, characterized in that, Comprising the following steps: Step 1) Prepare an aluminum alloy coating on one side of a copper strip by molten salt electroplating; obtain a copper strip plated with aluminum alloy; Step 2) Process the copper strip plated with aluminum alloy to form the aluminum alloy plated copper transition terminal; and make the aluminum alloy coating located on the inner surface of the aluminum alloy plated copper transition terminal; Step 3) Install the aluminum alloy plated copper transition terminal at the end of the aluminum cable.

8. The preparation method according to claim 7, characterized in that, The method for preparing an aluminum alloy coating on one side of a copper strip by molten salt electroplating comprises: 1) Clean the copper strip; and cover a masking material on one side surface of the copper strip; 2) Perform surface treatment on the aluminum anode; 3) Heat a mixed salt containing AlCl3, NaCl, KCl and gadolinium to melting to form a molten salt; 4) Use a copper strip as the cathode and insert it into the molten salt together with an aluminum anode for electroplating treatment; the electroplating temperature is 450 - 520 K, and the current density is 16 - 24 mA / cm 2 , and the electroplating time is 8 - 25 min; 5) Remove the masking material after electroplating is completed.

9. The preparation method according to claim 8, wherein, The cleaning of the copper strip includes successive alkali cleaning and acid cleaning; Preferably, the molar ratio of AlCl3:NaCl:KCl is 4:1:1 to 8:1:1, and the gadolinium content in the molten salt is 0.15 to 0.35%; Preferably, the thickness of the copper strip is 1 to 20 mm, and the thickness of the aluminum alloy coating is 10 to 26 μm.

10. The preparation method according to claim 8, wherein The preparation method further includes step (iii) of processing an aluminum cable socket portion on the copper-aluminum alloy plated transition terminal with the copper strip plated with aluminum alloy, and making the aluminum alloy coating located on the outer surface of the aluminum cable socket portion.

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