CN111243820A - Bronze process Nb3Sn superconducting wire joint and preparation method thereof - Google Patents
Bronze process Nb3Sn superconducting wire joint and preparation method thereof Download PDFInfo
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F6/00—Superconducting magnets; Superconducting coils
- H01F6/06—Coils, e.g. winding, insulating, terminating or casing arrangements therefor
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/04—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing coils
- H01F41/048—Superconductive coils
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R4/00—Electrically-conductive connections between two or more conductive members in direct contact, i.e. touching one another; Means for effecting or maintaining such contact; Electrically-conductive connections having two or more spaced connecting locations for conductors and using contact members penetrating insulation
- H01R4/58—Electrically-conductive connections between two or more conductive members in direct contact, i.e. touching one another; Means for effecting or maintaining such contact; Electrically-conductive connections having two or more spaced connecting locations for conductors and using contact members penetrating insulation characterised by the form or material of the contacting members
- H01R4/68—Connections to or between superconductive connectors
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R43/00—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R43/00—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors
- H01R43/04—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors for forming connections by deformation, e.g. crimping tool
- H01R43/048—Crimping apparatus or processes
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Abstract
Bronze process Nb3The Sn superconducting wire joint comprises a copper pipe, a Ta film, a superconducting joint connecting part and a supporting core from outside to inside. The Ta film is attached to the inner wall of the copper pipe, the supporting core is located in the center of the copper pipe, and the superconducting joint connecting portion is located between the Ta film and the supporting core. The preparation method of the superconducting wire joint comprises the following steps: (1) using FeCl3Solution etching of Nb to be joined3Copper at the wire inlet end and the wire outlet end of the Sn coil, Nb is exposed3A Nb multifilament in Sn wire and a support core; (2) dividing the multiple Nb wires into multiple bundles, and weaving the multiple Nb wires into one bundle; (3) inserting Ta filmThe copper pipe is arranged in the copper pipe and is attached to the inner wall of the copper pipe wall; inserting the woven Nb multi-filament bundles into a copper pipe; (4) mixing Nb powder and bronze alloy powder, and pouring into a mortar for grinding; (5) and pouring the mixed Nb powder and bronze alloy powder into a copper pipe inserted with Nb multifilaments, and sealing two ends of the copper pipe. Horizontally placing the copper pipe on a press machine for pressurization; (6) mixing Nb with3And carrying out high-temperature heat treatment on the Sn coil together with the copper pipes at the wire inlet end and the wire outlet end.
Description
Technical Field
The invention relates to a Nb3Sn superconducting wire joint and a preparation method thereof.
Background
With the rapid development of superconducting magnet technology, scientific research devices and facilities with ultrahigh magnetic fields are continuously available. These devices feature extremely high magnetic fields, which can be a significant challenge for superconducting magnet high-field coils that provide strong magnetic fields under extreme environmental multi-physical field operating conditions. At present, the low-temperature superconducting magnet in the high-intensity magnetic field device is mainly composed of NbTi and Nb3Sn superconducting coil, compared with low-temperature NbTi superconducting coil, Nb3The Sn has higher superconducting transition temperature which is more than 18K, the upper critical magnetic field can reach 25T at 4.2K, and the critical current density carried under the 4.2K/10T magnetic field is about 5 multiplied by 105A/cm2. However, the manufacturing process of the superconducting coil is quite complex, and the generated A15 crystal structure is an intermetallic compound, so that the superconducting coil is high in brittleness and hardness. At present, a plurality of process difficulties are limited to Nb3Use of Sn superconducting coils.
The bronze process and the internal tin process are currently used for preparing Nb3Sn superconducting wire is the most widely used method. The bronze process mainly uses tin bronze as a matrix of the superconducting wire. Inserting Nb alloy rod into the punched hole of the tin bronze base body, extruding and drawing the combined composite body for multiple times to obtain sub-components, bundling a plurality of sub-components together and loading the sub-components into a stable copper tube, extruding and drawing the copper tube to obtain the final size, and finally performing heat treatment on the wire at 600-800 ℃ to obtain A15 phase Nb3A Sn superconductor.
Nb3Sn superconducting magnets require superconducting joints to hold multiple independent Nb3The Sn magnet coil is connected. Because for Nb3The Sn low-temperature superconducting wire is used for winding a large superconducting magnet, and dozens or even hundreds of kilometers of superconducting wire are usually needed. Because of the limitations of the superconducting wire processing technology and equipment, it is extremely difficult and costly to manufacture a single superconducting wire several tens of kilometers long, so that the length of each actually manufactured superconducting wire is often several hundred meters to several kilometers, which requires the manufacture of a superconducting joint for connecting several superconducting wires. In addition, for the application occasions such as magnetic resonance, the requirements on magnet space and magnetic field uniformity are high, meanwhile, the superconducting magnet needs to be ensured to be capable of operating in a closed loop under a low-temperature environment, and a high-field superconducting joint needs to be manufactured. Nb for closed loop operation3Sn superconducting magnets, in particular for magnetic resonance high field superconducting magnets requiring high magnetic field homogeneity, require Nb3The superconducting joint of Sn has a low resistance characteristic. Because of Nb3After heat treatment, Sn superconductors have a brittle ceramic phase, which makes it difficult to handle on superconducting wires, which would otherwise be Nb3Non-restorable damage in Sn superconductors further limits high performance Nb3And manufacturing the Sn superconducting magnet.
The fabrication process of superconducting joints is very diverse, such as brazing, cold welding, diffusion welding, fusion welding, sintering, etc. Among them, the brazing, fusion welding and cold pressure welding processes appear earlier, and are widely used at present; diffusion welding and sintering processes have emerged relatively late and are currently at a substantially laboratory level. Due to the complex physical structure and special physical properties of superconducting materials, it is very difficult to ensure that the properties of the joined joint portions are not changed at all. The physical construction of the joint is generally quite complex compared to the bus bar. The application of chemical and thermomechanical processes to the filaments perturbs the chemical and microstructure, locally changing the superconducting properties, most notably their upper critical field (H c2) and critical current density (Jc).
The superconducting joint in the superconducting magnet is a very fragile and easily damaged part in a magnet system, and the intersection of the whole magnet system is influenced by production stop caused by joint problems in the manufacturing process of the superconducting magnetAnd (5) paying. Mainly because of Nb3The Sn superconducting magnet is manufactured by a reaction-winding method, namely unreacted Nb3The Sn superconducting wire is first wound into a coil, and then the coil is subjected to a long-time high-temperature heat treatment to generate Nb3A Sn superconducting phase. The process is very complex, and factors influencing the final superconducting magnet are many, and a plurality of factors comprise heat treatment temperature, temperature uniform area, stress introduced by heat treatment, volume fraction of superconducting phase generated by reaction and the like. At Nb3In the manufacturing process of the Sn superconducting joint, the Sn superconducting joint not only needs to undergo the severe heat treatment reaction, but also ensures that the superconducting joint part can generate superconducting connection, the superconducting joint can meet the requirements of critical magnetic field intensity, conduction not lower than the excitation current of a superconducting magnet, and extremely low resistance not higher than the E-12 magnitude, and simultaneously also meets the stress requirements of a strong magnetic field in the low-temperature excitation process of the superconducting joint, extremely low temperature, large current and other polar environment multi-field coupling effects.
At present about Nb3In the method for producing Sn superconducting joints, Nb after heat treatment reaction was used by Airco of America3The Sn wire joint is directly subjected to resistance welding, and the joint resistance is only 10-8Omega. Chemical vapor deposition method for preparing Nb at Washington university in America3A Sn superconducting joint having a critical current density of 500000A/cm under a 5T comparative magnetic field2. This method has high requirements for process and equipment, and is not suitable for engineering application. Patent CN201010221920.8 adopts a deposition method to prepare Nb3The Sn superconducting joint needs an electroplating process, and the process is complex and is not an environment-friendly treatment method.
Disclosure of Invention
The invention aims to overcome the defects of high equipment requirement, complex process and unfriendly environment in the prior art, and provides a bronze process Nb3Sn superconducting wire joint and a preparation method thereof. The invention has simple and reliable process and can obtain the low-resistance Nb3The Sn superconducting joint is suitable for industrial manufacture.
The purpose of the invention is realized by the following technical scheme.
Bronze process Nb3The Sn superconducting wire joint comprises a Cu pipe, a Ta film, a superconducting joint connecting part and a supporting core from outside to inside, wherein the Ta film is attached to the inner wall of the Cu pipe, the supporting core is positioned in the center of the copper pipe, and the superconducting joint connecting part is positioned between the supporting core and the Ta film.
The superconducting joint connecting part is formed by sintering Nb multifilaments and Nb generated by metal powder3Sn bulk material. The Nb multiple wires are combined and woven and are mutually spliced to form a multi-bundle wire strand. Current at said Nb3The Sn bulk material forms a resistance-free or low-resistance superconducting connection.
Nb of the invention3The Sn superconducting wire joint is generated by carrying out high-temperature heat treatment diffusion reaction on Nb multifilaments, Nb powder and bronze alloy powder.
Bronze Process Nb of the invention3Sn superconducting wire joint applied to connecting two Nb with limited length3Sn wire, or for a plurality of Nb3The series connection of the Sn coils forms a superconducting connection of current.
The joint resistance testing method comprises the following steps: bronze process Nb3Winding Sn wire into Nb3Sn coil, the incoming wire and the outgoing wire of which are made into Nb3And the Sn joint forms a closed loop, and adopts an electromagnetic induction method to induce current in the joint loop and test the current attenuation so as to calculate the resistance of the joint.
The invention adopts bronze process Nb3The preparation method of the Sn superconducting wire joint comprises the following steps:
(1) using FeCl3Solution etching of Nb to be joined3The copper of the inlet end and the outlet end of the Sn coil has the corrosion section length of 2cm-20cm and exposes Nb3A Nb multifilament in Sn wire and a support core;
(2) corroding Nb3Multiple Nb wires in the wire inlet end and the wire outlet end of the Sn coil are divided into multiple beams, and the multiple beams are woven pairwise to form a beam;
(3) and inserting the Ta film into the copper pipe, and attaching the Ta film to the inner wall of the copper pipe to form an inner wall layer. Then inserting the woven Nb multi-filament bundles into the copper pipe;
(4) mixing Nb powder and bronze alloy powder, pouring into a mortar, and grinding for half an hour to uniformly mix the Nb powder and the bronze alloy powder;
(5) and pouring the mixed Nb powder and bronze alloy powder into a copper pipe inserted with Nb multifilaments, and tightly pressing and sealing two ends of the copper pipe by using pressure clamps. Then horizontally placing the copper pipe on a press machine for pressurizing, and compacting the Ta film, the Nb multi-filament bundle, the Nb powder and the bronze alloy powder in the copper pipe;
(6) mixing Nb with3And carrying out high-temperature heat treatment on the Sn coil together with the copper pipes at the wire inlet end and the wire outlet end at 640-670 ℃ for 200-220 h to form the joint. Nb is generated at the joint part through high-temperature diffusion reaction3And Sn is connected in a superconducting way.
Wherein the bronze alloy powder is copper-tin alloy powder, the molar ratio of copper to tin is 10:1-1:1, and the molar ratio of Nb powder to Sn in the bronze powder is 6:1-0.5: 1. The grain sizes of the Nb powder and the bronze powder are micron-sized to nanometer-sized.
Wherein the wall thickness of the copper pipe is 0.2mm-1mm, and the thickness of the Ta film is 0.1mm-1 mm.
Wherein, the pressure is 0.1 ton to 10 tons by horizontally placing the pressure machine to press the joint.
The bronze alloy powder adopted by the invention is obtained by smelting copper and tin metals. Pure Sn becomes liquid at 230 ℃ or higher, and if the pure Sn is directly subjected to heat treatment, the pure Sn is melted when the temperature exceeds the melting point of Sn, the liquid Sn gradually volatilizes, a liquid-solid interface is formed, and the reaction with solid Nb is difficult to obtain the required Nb3A Sn superconducting phase. Moreover, the diffusion reaction is carried out under a liquid-solid interface, the chemical reaction is difficult to occur according to the temperature interval and the atomic component interval on the binary phase diagram of Nb and Sn, and the Nb and Sn reaction easily generates a plurality of heterogeneous phases, such as Nb6Sn5、NbSn2And (3) impurity phase. By adopting the quantitative copper-tin alloy powder with accurate chemical percentage, Sn atoms and copper atoms form a solid solution in a solid state form, so that the problem that Sn melts beyond a melting point can be avoided. According to the invention, the Nb powder and the copper-tin alloy powder are uniformly mixed, the thermal diffusion reaction among solid reactants occurs in the high-temperature thermal treatment diffusion reaction, and the thermal diffusion reaction is easier to control to be carried out according to the stoichiometric ratio and the temperature range, so that the required Nb is obtained3And (3) Sn products.
Drawings
FIG. 1 is a schematic cross-sectional view of a Nb3Sn superconducting wire;
FIG. 2FeCl3Schematic cross-sectional view of the end of the solution-etched Nb3Sn superconducting wire;
FIG. 3 is a schematic diagram of an Nb multifilaments construction with splices to each other;
FIG. 4 inventive Nb3The structure schematic diagram of a copper pipe and a Ta film of the Sn superconducting wire joint;
FIG. 5Nb3The Nb and bronze powder in the Sn bulk material part are distributed schematically;
FIG. 6 is a schematic diagram of an Nb3Sn superconducting joint structure of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings and the detailed description.
As shown in FIG. 6, the bronze Process Nb of the present invention3The structure of the Sn superconducting wire joint is as follows from outside to inside respectively: copper pipe, Ta film, superconductive joint connecting portion and support core. The Ta film is attached to the inner wall of the Cu pipe, the supporting core is located in the center of the copper pipe, and the superconducting joint connecting portion is located between the supporting core and the Ta film.
The superconducting joint connection part is formed by Nb multifilaments and sintered Nb3Sn bulk material. The Nb multiple wires are combined and woven and are mutually spliced to form a multi-bundle wire strand. Nb3The Sn joint is generated by Nb multifilaments, Nb powder and bronze alloy powder through high-temperature heat treatment diffusion reaction,
bronze process Nb of the invention3The preparation method of the Sn superconducting wire joint comprises the following steps:
Nb3the structure of the Sn superconducting wire is shown in fig. 1. The wire inlet end and the wire outlet end of the superconducting coil are fixed, and the length of a joint is reserved. First using FeCl3Solution corrosion of Nb3The copper at the wire inlet end and the wire outlet end of the Sn coil has the corrosion section length of 2cm-20cm, and Nb multifilaments and a supporting core are exposed, as shown in figure 2. And cleaning the Nb multifilaments and the supporting core by using deionized water, cleaning the Nb multifilaments and the supporting core by using alcohol, and placing the cleaned Nb multifilaments and the supporting core until the Nb multifilaments and the supporting core are dried. Then, the Nb multifilaments at the wire inlet end and the wire outlet end are divided into a plurality of bundles, and part of the multifilaments of one bundle are taken to be crossed with part of the multifilaments of the other bundleThe fork is knitted into a new bundle as shown in fig. 3. And continuously weaving other multiple filaments until all the multiple filaments are woven, and arranging the support cores in parallel. As shown in FIG. 4, a Ta film was inserted into a copper tube and adhered to the inside of the tube arm to form an inner wall layer. The Ta layer can prevent the atoms of the inner layer from inter-diffusing into the copper of the outer layer during the subsequent high-temperature heat treatment diffusion reaction, and the purity of the copper layer of the outermost layer is changed. Wherein the thickness of the Ta film is 0.1mm-1mm, and the thickness of the copper tube is 0.2mm-1 mm. And then inserting the woven Nb filaments into the copper pipe for dispersion.
Mixing Nb powder and bronze alloy powder, and then pouring into a mortar for grinding for half an hour to be uniformly mixed. Wherein the bronze alloy powder is copper-tin alloy powder, the molar ratio of copper to tin is 10:1-1:1, and the molar ratio of Nb to Sn in the bronze powder is 6:1-0.5: 1. The Nb powder and the bronze powder have the size from micron to nanometer.
The mixed Nb powder and bronze alloy powder were then poured into a copper tube with Nb multifilaments inserted, as shown in fig. 5. The two ends of the copper pipe are pressed tightly by a pressure clamp for sealing. And horizontally placing the copper pipe on a press machine for pressurizing, wherein the pressure is 0.1 ton-10 ton, and compacting the Ta film, the Nb multi-strand bundle, the Nb powder and the bronze alloy powder in the copper pipe. Last Nb3And carrying out high-temperature heat treatment on the Sn coil together with the copper pipes at the wire inlet end and the wire outlet end, wherein the heat treatment temperature is 640-670 ℃, and the heat preservation time is 200-220 h, so as to form the joint. Nb is generated at the joint part through high-temperature diffusion reaction3Sn, thereby forming a superconducting connection, as shown in fig. 6. The high-temperature heat treatment adopts a mature heat treatment process of the superconducting wire.
Example one
Firstly, FeCl with the mass fraction of 50 percent is used3Solution corrosion of Nb3And copper at the two ends of the inlet wire and the outlet wire of the Sn coil has the corrosion section length of 2cm, and Nb multifilaments and a support core are exposed. And cleaning the Nb multifilaments and the supporting core by using deionized water, then cleaning the Nb multifilaments and the supporting core by using alcohol, and placing the Nb multifilaments and the supporting core until the Nb multifilaments and the supporting core are dried. Then, the Nb multi-filaments of the two wires are divided into 10 bundles, part of the multi-filaments of one bundle and part of the multi-filaments of the other bundle are respectively woven into a new bundle in a crossing manner, other multi-filaments are continuously woven until all the multi-filaments are woven, and the support cores are arranged in parallel. Inserting 0.1mm Ta film into 0And 2 mm-wall-thickness copper pipe, and an inner wall layer is formed by adhering the copper pipe to the inner side of the pipe arm. And then inserting the woven Nb multi-filament bundles into the copper pipe for dispersion. 10g of 45 micron Nb powder and 45 micron bronze alloy powder with the molar ratio of copper to tin of 10:1 are mixed, and the molar ratio of Nb to Sn in the bronze powder is 6: 1. Then pouring the mixture into a mortar for grinding for half an hour and uniformly mixing. And then pouring the mixed Nb powder and bronze alloy powder into a copper pipe inserted with Nb multifilaments, and tightly pressing and sealing two ends of the copper pipe by using pressure pliers. The copper tube was horizontally placed on a press and a pressure of 10 tons was applied to compact the individual material components inside. Finally, the copper pipe and Nb are processed3And carrying out high-temperature heat treatment on the Sn coils together, wherein the heat treatment temperature is 640 ℃, and the heat preservation time is 200h, so as to form the joint. Nb is generated at the joint part through high-temperature diffusion reaction3And Sn is connected in a superconducting way. The high-temperature heat treatment adopts a mature heat treatment process of the superconducting wire. The test shows that the joint resistance is 8.5 multiplied by 10-12Ω。
Example two
Firstly, FeCl with the mass fraction of 30 percent is used3Solution 5 etching Nb3And copper at the two ends of the Sn coil incoming and outgoing lines has the corrosion section length of 20cm, and Nb multifilaments and the supporting core are exposed. And cleaning the Nb multifilaments and the supporting core by using deionized water, cleaning the Nb multifilaments and the supporting core by using alcohol, and placing until the Nb multifilaments and the supporting core are dried. Two pieces of Nb are added3The Nb multi-filaments of the Sn wire are divided into 15 bundles, part of the multi-filaments of one bundle and part of the multi-filaments of the other bundle are respectively woven into a new bundle in a crossing manner, other multi-filaments are continuously woven until all the multi-filaments are woven, and the support cores are arranged in parallel. A Ta film of 1mm was inserted into a copper tube of 1mm thickness, and adhered to the inner side of the tube arm to form an inner wall. And then inserting the woven Nb multi-filament bundles into the copper pipe for dispersion. 10g of 0.5 micron Nb powder and 45 micron bronze alloy powder with a 1:1 molar ratio of copper to tin were mixed, and the molar ratio of Nb to Sn in the bronze powder was 0.5: 1. And pouring the mixed Nb powder and bronze alloy powder into a mortar for grinding for half an hour, then pouring the mixed Nb powder and bronze alloy powder into a copper pipe inserted with Nb multifilaments, and tightly pressing and sealing two ends of the copper pipe by using a pressure clamp. The copper pipe is horizontally placed on a press machine, and 0.1 ton of pressure is applied to tightly compact each material component in the copper pipe. Finally, the copper pipe and Nb are processed3Sn coils are commonly carried outAnd (4) performing high-temperature heat treatment at 670 ℃ for 220h to form the joint. Nb is generated at the joint part through high-temperature diffusion reaction3And Sn is connected in a superconducting way. The high-temperature heat treatment adopts a mature heat treatment process of the superconducting wire. Resistance to the tested joint is 5.5X 10-12Ω。
EXAMPLE III
Firstly, FeCl with the mass fraction of 40 percent is used3Solution 5 etching Nb3And copper at the two ends of the Sn coil incoming and outgoing lines has the corrosion section length of 10cm, and Nb multifilaments and the supporting core are exposed. And cleaning the Nb multifilaments and the supporting core with deionized water for three times, cleaning the Nb multifilaments and the supporting core with alcohol for three times, and placing until the Nb multifilaments and the supporting core are dry. Then the Nb multifilaments of the two threads are divided into 15 bundles, part of the multifilaments of one bundle and part of the multifilaments of the other bundle are respectively woven into a new bundle in a crossing manner, other multifilaments are continuously woven until all the multifilaments are woven, and the support cores are arranged in parallel. A Ta film of 0.5mm was inserted into a copper tube of 0.5mm thickness, and adhered to the inner side of the tube arm to form an inner wall. And then inserting the woven Nb multi-filament bundles into the copper pipe for dispersion. 10g of 0.5 micron Nb powder and 45 micron bronze alloy powder with a 5:1 molar ratio of copper to tin were mixed, the molar ratio of Nb to Sn in the bronze powder being 3: 1. Then pouring the mixture into a mortar for grinding for half an hour and uniformly mixing. Then pouring the mixed Nb powder and bronze alloy powder into a copper pipe inserted with Nb multifilaments, and tightly pressing and sealing two ends of the copper pipe by using pressure pliers. The joint portion was then placed flat on a press and 5 tons of pressure were applied to compact the individual material components inside. Finally, the copper pipe and Nb are processed3And carrying out high-temperature heat treatment on the Sn coils together, wherein the heat treatment temperature is 660 ℃, and the heat preservation time is 210h, so as to form the joint. Nb is generated at the joint part through high-temperature diffusion reaction3And Sn is connected in a superconducting way. The high-temperature heat treatment adopts a mature heat treatment process of the superconducting wire. Resistance to the tested joint was 6.5X 10-12Ω。
Claims (7)
1. Bronze process Nb3An Sn superconducting wire joint, characterized in that: the joints are respectively from outside to inside: the device comprises a copper pipe, a Ta film, a superconducting joint connecting part and a supporting core; the Ta film is attached to the inner wall of the copper pipe, and the supporting core is positioned on the copperThe superconducting joint connecting part is positioned between the Ta film and the support core; nb3The Sn superconducting wire joint is generated by carrying out high-temperature heat treatment diffusion reaction on Nb multifilaments, Nb powder and bronze alloy powder.
2. Bronze process Nb according to claim 13An Sn superconducting wire joint, characterized in that: the superconducting joint connecting part is formed by Nb multifilaments and Nb3Composite of Sn bulk material, Nb3The Sn bulk material is generated by sintering metal powder; current at said Nb3The Sn bulk material forms a resistance-free or low-resistance superconducting connection.
3. Bronze process Nb according to claim 13An Sn superconducting wire joint, characterized in that: the Nb multiple wires are combined and woven and are mutually spliced to form a multi-bundle wire strand.
4. Bronze process Nb according to claim 13The preparation method of the Sn superconducting wire joint is characterized by comprising the following steps: the preparation steps are as follows:
(1) using FeCl3Solution etching of Nb to be joined3The copper at the wire inlet end and the wire outlet end of the Sn coil has the corrosion section length of 2cm-20cm and exposes Nb3A Nb multifilament in Sn wire and a support core;
(2) corroding Nb3Multiple Nb wires in the wire inlet end and the wire outlet end of the Sn coil are divided into multiple beams, and the multiple beams are woven pairwise to form a beam;
(3) inserting a Ta film into the copper pipe, and attaching the Ta film to the inner wall of the copper pipe to form an inner wall layer; then inserting the woven Nb multi-filament bundles into the copper pipe;
(4) mixing Nb powder and bronze alloy powder, pouring into a mortar, and grinding for half an hour to uniformly mix the Nb powder and the bronze alloy powder;
(5) pouring the mixed Nb powder and bronze alloy powder into a copper pipe inserted with Nb multifilaments, and tightly pressing and sealing two ends of the copper pipe by using a pressure clamp; then horizontally placing the copper pipe on a press machine for pressurizing, and compacting the Ta film, the Nb multi-filament bundle, the Nb powder and the bronze alloy powder in the copper pipe;
(6) will Nb3The Sn coil together with the copper pipes at the wire inlet end and the wire outlet end are subjected to high-temperature heat treatment at 640-670 ℃, the heat preservation time is 200-220 h, and the joint part generates Nb through high-temperature diffusion reaction3And Sn is connected in a superconducting way.
5. Bronze process Nb according to claim 43The preparation method of the Sn superconducting wire joint is characterized by comprising the following steps: the Nb powder and the bronze alloy powder are added in proportion, the bronze alloy powder is copper-tin alloy powder, the molar ratio of copper to tin is 10:1-1:1, and the molar ratio of Nb to Sn in the bronze powder is 6:1-0.5: 1; the grain sizes of the Nb powder and the bronze powder are micron-sized to nanometer-sized.
6. Bronze process Nb according to claim 43The preparation method of the Sn superconducting wire joint is characterized by comprising the following steps: the thickness of the Ta film is 0.1mm-1mm, and the wall thickness of the copper pipe is 0.2mm-1 mm.
7. Bronze process Nb according to claim 43The preparation method of the Sn superconducting wire joint is characterized by comprising the following steps: the pressure of the press is 0.1 ton to 10 tons.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114694893A (en) * | 2022-05-31 | 2022-07-01 | 西部超导材料科技股份有限公司 | Preparation method of superconducting cable for quantum computer |
| CN117543236A (en) * | 2023-12-07 | 2024-02-09 | 中国科学院赣江创新研究院 | Superconducting joint and preparation method thereof |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114694893A (en) * | 2022-05-31 | 2022-07-01 | 西部超导材料科技股份有限公司 | Preparation method of superconducting cable for quantum computer |
| CN114694893B (en) * | 2022-05-31 | 2022-09-09 | 西部超导材料科技股份有限公司 | Preparation method of superconducting cable for quantum computer |
| CN117543236A (en) * | 2023-12-07 | 2024-02-09 | 中国科学院赣江创新研究院 | Superconducting joint and preparation method thereof |
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