NbTi superconducting joint preparation device

Abstract

The utility model provides an NbTi superconducting joint preparation device. The NbTi superconducting joint preparation device comprises a first container and a second container, the first container and the second container are detachably communicated through a gate valve; the first container is used for storing an acid solution, and the second container is used for storing molten lead bismuth; the second container comprises an air inlet, an air outlet and a penetration hole for penetration of the NbTi wire cluster; the air inlet is used for introducing inert gas, and the exhaust port is used for exhausting replaced air. Through free connection and disconnection between the two containers, the superconducting wire is subjected to acid pickling and welding in sequence, the acid-pickled wire is guaranteed not to be oxidized through an inert gas environment, the whole preparation process is smooth and rapid, operation is easy, the device is easy to assemble and disassemble, and the technical requirement for operators is low.

Description

Technical Field

[0001] The utility model relates to the technical field of superconducting joint preparation, in particular to a NbTi superconducting joint preparation device. Background Art

[0002] Superconducting joint technology is one of the key technologies of superconducting magnets. Superconducting joints undertake the important task of connecting the electrical circuit of the magnet and are widely used in magnets that require high uniformity of tightly wound solenoid coils, such as magnetic resonance imaging magnets (MRI), nuclear magnetic resonance magnets (NMR) and magnets operating in a closed loop. The performance of superconducting joints directly determines the stable operation of the magnet, and the performance of superconducting joints is affected by many factors, including the external magnetic field environment, its own mechanical structure, and assembly welding process. How to design a device to reduce the resistance of superconducting magnet joints is of great significance.

[0003] At present, the main low-temperature superconducting joints are NbTi superconducting joints, Nb3Sn superconducting joints and NbTi-Nb3Sn mixed superconducting joints, among which NbTi superconducting joints are the most widely used. NbTi superconducting materials have no anisotropy, high critical current density, good plasticity, upper critical magnetic field R = V / I, critical temperature Tc = 9.2K. It has excellent mechanical properties and processing plasticity in medium and low magnetic fields, and the processing cost of NbTi is much lower than other superconducting materials.

[0004] At present, the main methods for making NbTi superconducting joints are: brazing, cold pressure welding, diffusion welding, sintering, solder base replacement method, etc. Among them, the brazing method uses molten solder to fill the gap, the equipment is simple and easy to operate, the cost is low and it is widely used, but the strength of the brazed joint is low, and the large difference between the parent material and the brazing material will make its corrosion resistance poor. Cold pressure welding removes the copper, oxide layer and organic matter outside the NbTi superconducting core through nitric acid and hydrofluoric acid solution, and then twists the two superconducting filaments together and inserts them into Cu, Nb, or NbTi tubes. Under the sufficiently large pressure given by the hydraulic press, the NbTi cores will be connected together. This method is simple and easy to operate, but after pickling, the superconducting wire is easily oxidized when exposed to air. The process performance is not very stable and the application range is small. The sintering method is to carry out structural filling, which can make the texture of the joint part similar to that of the parent material at the microscopic level, but the process is complicated, the operation is difficult, and it is not widely used. The solder base replacement method makes superconducting joints by replacing the matrix material, which makes the superconducting wire and the solder fully contact and the joint resistance is very small, but the process is relatively complicated and the preparation time is long.

[0005] Therefore, this device combines the pickling method with the solder base replacement method, and uses an acidic solution to remove the copper base in the superconducting wire. The device is a vacuum environment, and the superconducting wire is not in contact with the air. The superconducting wire is directly immersed in the molten solder to prevent the possibility of oxidation, reduce the joint resistance, and simplify the preparation process. Utility Model Content

[0006] The technical problem to be solved by the utility model is how to eliminate the problem of easy oxidation in the preparation process of superconducting joints, and at the same time simplify the preparation process and reduce the preparation time.

[0007] The utility model solves the above technical problems through the following technical means:

[0008] A NbTi superconducting joint preparation device comprises a first container and a second container; the first container and the second container are detachably connected via a gate valve; the first container is used to store an acid solution, and the second container is used to store molten lead and bismuth;

[0009] The second container comprises an air inlet, an air outlet, and a penetration hole for the NbTi filament cluster to penetrate; the air inlet is used to introduce inert gas, and the air outlet is used to exhaust the displaced air.

[0010] The utility model allows the superconducting wire to be pickled and soldered in sequence by freely switching between two containers, and ensures that the wire will not be oxidized after pickling through an inert gas environment. The entire preparation process is smooth and fast, the operation is simple, the assembly and disassembly of the device is simple and easy to achieve, and the technical requirements for operators are low.

[0011] Furthermore, the gate valve includes a gate plate, a first joint, a second joint, and an intermediate flange; the first joint and the second joint are fixed by the intermediate flange; the first joint is configured to be sealed and assembled with the connection port of the first container, and the second joint is configured to be sealed and assembled with the connection port of the second container; the gate plate and the intermediate flange form a gate, thereby realizing the connection and disconnection of the first container and the second container.

[0012] Furthermore, the first joint and the second joint have the same structure, both comprising a flange and a sleeve nested and assembled with the connecting port of the first container or the second container; the first joint, the second joint and the intermediate flange are axially connected.

[0013] Furthermore, the middle flange is provided with a U-shaped slot, and the gate plate is plugged into and matched with the U-shaped slot to realize the connection and disconnection between the first container and the second container.

[0014] Furthermore, it also includes a heating unit for heating the second container.

[0015] Furthermore, the heating unit is a heating wire, which is wound around the outside of the second container.

[0016] Furthermore, the second container is provided with a sealing cover, and the air inlet, the exhaust port and the penetration hole are all provided on the sealing cover.

[0017] Furthermore, curved pipe sections are installed at the air inlet, the air outlet and the penetration hole.

[0018] Furthermore, the sleeve includes an annular cavity formed by two layers of inner and outer sleeves, and the connecting port of the first container or the second container is embedded in the annular cavity.

[0019] Furthermore, a sealing ring is placed at the bottom of the annular cavity, and the connecting port of the first container or the second container is pressed against the sealing ring.

[0020] The advantages of the utility model are:

[0021] The utility model allows the superconducting wire to be pickled and soldered in sequence by freely switching between two containers, and ensures that the wire will not be oxidized after pickling through an inert gas environment. The entire preparation process is smooth and fast, the operation is simple, the assembly and disassembly of the device is simple and easy to achieve, and the technical requirements for operators are low. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the explosion structure of the device in the embodiment of the utility model;

[0023] Figure 2 It is a schematic diagram of the structure after assembly of the device in the embodiment of the utility model. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the utility model clearer, the technical solution in the embodiments of the utility model will be clearly and completely described below in combination with the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] This embodiment provides a NbTi superconducting joint preparation device, Figure 1 For the exploded view, Figure 2 The figure is an assembled figure, the device includes a first container 1 and a second container 2; the first container 1 and the second container 2 are detachably connected through a gate valve 3; the first container 1 is used to store an acid solution, and the second container 2 is used to store molten lead and bismuth. In this embodiment, the first container 1 and the second container 2 can be assembled in an up-down or left-right manner, and the purpose of this solution can be achieved. Figure 1 As shown, in this embodiment, an up-and-down method is adopted, with the second container 2 on the top to prevent the molten lead and bismuth from flowing out.

[0026] Specifically, the second container 2 is made of metal, and one end of the second container 2 is a connection port, which is assembled with the gate valve 3. In order to facilitate disassembly and sealing, the connection port of the second container 2 is set to a cylindrical tube shape, which is convenient for plugging with the gate valve 3 (the structure of the gate valve 3 is shown below). The other end of the second container 2 can be closed or covered. In order to facilitate cleaning the inside of the container, this embodiment is set to a covered type, and an air inlet 22, an exhaust port 23, and a penetration hole 24 for the NbTi filament cluster to penetrate are opened on the cover 21; the air inlet 22 is used to pass inert gas, and the exhaust port 23 is used to discharge the replaced air, so that there is no oxygen in the second container 2 to avoid oxidation of the NbTi superconducting joint. In order to ensure the sealing of the second container 2 and facilitate connection with the inert gas charging equipment, a bend or a straight pipe is welded at the air inlet 22, the exhaust port 23, and the penetration hole 24. The bend acts as a joint, and a one-way valve can be installed on the bend or straight pipe of the air inlet 22 and the exhaust port 23 to improve the sealing.

[0027] The first container 1 is also made of metal, and its shape and volume can be the same as or different from the second container 2. The socket of the first container 1 and the gate valve 3 are the same as those of the second container 2. However, the other end of the first container 1 is a closed end, and a drain port can be opened at the bottom of the first container 1, and a valve 11 is installed at the drain port to facilitate the discharge of the acidic solution therein. Of course, the drain port can also be omitted, and the acidic solution can be directly poured out from the socket.

[0028] The gate valve 3 includes a gate plate 31, a first joint 32, a second joint 33, and an intermediate flange 34; the first joint 32 and the second joint 33 are fixed by the intermediate flange 34; the first joint 32 is configured to be sealed and assembled with the connection port of the first container 1, and the second joint 33 is configured to be sealed and assembled with the connection port of the second container 2; the gate plate 31 and the intermediate flange 34 form a gate, thereby realizing the connection and disconnection of the first container 1 and the second container 2. Specifically, the first joint 32 and the second joint 33 have the same structure, both including a flange 331 and a sleeve 332 nested and assembled with the connection port of the first container 1 or the second container 2; the sleeve 332 includes an annular cavity formed by two layers of inner and outer sleeves 332, and the connection port of the first container 1 or the second container 2 is embedded in the annular cavity. Multiple screw holes are opened on the flange 331 of the intermediate flange 34, the first joint 32 and the second joint 33, and the three can be fixed by bolts. In order to ensure the sealing performance, a sealing ring (not shown in the figure) is placed at the bottom of the annular cavity, and the connection port of the first container 1 or the second container 2 is pressed against the sealing ring.

[0029] In this embodiment, the middle flange 34 is provided with a U-shaped slot, and the gate plate 31 is plugged into the U-shaped slot. When the gate plate 31 is inserted into the U-shaped slot, the first container 1 and the second container 2 are separated. When the gate plate 31 is pulled out, the first container 1 and the second container 2 are connected.

[0030] In order to ensure the melting of molten lead and bismuth, the present embodiment further includes a heating unit 4 for heating the second container 2. The heating unit 4 is a heating wire, which is wound around the outside of the second container 2. The second container 2 can be heated by powering on.

[0031] When the device of this embodiment is used, first, a sufficient amount of acid solution is poured into the first container 1, and then the first container 1, the gate valve 3, and the second container 2 are assembled in sequence. At this time, the gate plate 31 is in the withdrawn state, the first container 1 is connected to the second container 2, and the second container 2 is injected with molten lead and bismuth. Next, an inert gas is injected into the second container 2. After the air in the second container 2 is replaced, the superconducting wire is inserted from the penetration hole 24 and reaches the first container 1 through the gate valve 3. The superconducting wire is immersed in the acid solution for a period of time and then withdrawn so that the pickled superconducting wire is located in the second container 2. At this time, the gate plate 31 is pushed in to disconnect the second container 2 from the first container 1. At this time, molten lead and bismuth can be injected through the exhaust port 23 (the injection of inert gas can be stopped at this time. With the injection of molten lead and bismuth, the inert gas in the second container 2 will be slowly discharged). If the ambient temperature is low, the heating wire can be connected to the power supply to ensure the molten state of the molten lead and bismuth. At this time, the superconducting wire is immersed in the molten lead and bismuth, and can be withdrawn after meeting the requirements. At this point, the preparation of the superconducting wire is completed. During the preparation process, the superconducting wire after pickling does not come into contact with air and will not be oxidized. The entire preparation process is fast and safe, and the device is easy to disassemble and clean. In this embodiment, the exhaust port 23 is used as the injection port for molten lead and bismuth, which can reduce the number of openings of the cover 21 and reduce the risk of air leakage.

[0032] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A NbTi superconducting joint preparation device, characterized in that: The invention comprises a first container (1) and a second container (2); the first container (1) and the second container (2) are detachably connected via a gate valve (3); the first container (1) is used to store an acid solution, and the second container (2) is used to store molten lead and bismuth; The second container (2) comprises an air inlet (22), an air outlet (23), and a penetration hole (24) for the NbTi filament cluster to penetrate; the air inlet (22) is used to introduce inert gas, and the air outlet (23) is used to exhaust the displaced air.

2. A NbTi superconducting joint preparation device according to claim 1, characterized in that: The gate valve (3) comprises a gate plate (31), a first joint (32), a second joint (33), and an intermediate flange (34); the first joint (32) and the second joint (33) are fixed via the intermediate flange (34); the first joint (32) is configured to be sealed and assembled with the connection port of the first container (1), and the second joint (33) is configured to be sealed and assembled with the connection port of the second container (2); the gate plate (31) and the intermediate flange (34) form a gate, thereby realizing the connection and disconnection of the first container (1) and the second container (2).

3. A NbTi superconducting joint preparation device according to claim 2, characterized in that: The first joint (32) and the second joint (33) have the same structure, both comprising a flange (331) and a sleeve (332) nested and assembled with the connecting port of the first container (1) or the second container (2); the first joint (32), the second joint (33) and the intermediate flange (34) are axially connected.

4. A NbTi superconducting joint preparation device according to claim 2 or 3, characterized in that: The intermediate flange (34) is provided with a U-shaped slot, and the gate plate (31) is plugged into and matched with the U-shaped slot to realize the connection and disconnection of the first container (1) and the second container (2).

5. A NbTi superconducting joint preparation device according to any one of claims 1 to 3, characterized in that: The second container (2) is provided with a sealing cover (21), and the air inlet (22), the air outlet (23) and the penetration hole (24) are all provided on the sealing cover (21).

6. A NbTi superconducting joint preparation device according to claim 5, characterized in that: Bent pipe sections are installed at the air inlet (22), the air outlet (23) and the penetration hole (24).

7. A NbTi superconducting joint preparation device according to claim 3, characterized in that: The sleeve (332) comprises an annular cavity formed by two layers of inner and outer sleeves, and the connecting port of the first container (1) or the second container (2) is embedded in the annular cavity.

8. A NbTi superconducting joint preparation device according to claim 7, characterized in that: A sealing ring is placed at the bottom of the annular cavity, and the connecting port of the first container (1) or the second container (2) is pressed against the sealing ring.

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