Preparation method for bronze-process nb3sn superconducting wire, and superconducting wire

Abstract

Disclosed in the present application are a preparation method for a bronze-process Nb3Sn superconducting wire, and a superconducting wire. The preparation method comprises: placing a bronze rod into an Nb tube, placing the Nb tube into a bronze tube, and performing rotary swaging, drawing and annealing to prepare a bronze / Nb single core rod; bundling up hundreds of bronze / Nb single core rods in a hexagonal close-packed manner and then coating same with a barrier layer, and then placing the bronze / Nb single core rods into a copper tube to form a final billet; and heating the final billet and then sequentially performing extruding, drawing and intermediate annealing thereon, so as to obtain a bronze-process Nb3Sn superconducting wire having ring-shaped core filaments. By means of the present application, an Nb core filament changes from a solid columnar shape to a hollow tubular shape, thereby increasing the interaction area between Nb and a bronze matrix, increasing the reaction rate of Nb with Sn in the bronze matrix during a phase-formation heat treatment, and shortening the reaction time.

Description

Method for preparing bronze-process niobium-tin superconducting wire and superconducting wire

[0001] The present application relates to the field of metal processing technology, and in particular to a method for preparing a bronze-process niobium-tin superconducting wire and the superconducting wire. Background Art

[0002] Bronze-processed niobium-tin (Nb3Sn) superconducting wire is an important material for making high-field magnets with a field strength greater than 10T. The magnets produced need to be wound first and then heat-treated to generate the Nb3Sn superconducting phase. The reaction between tin (Sn) and niobium (Nb) is a solid-phase diffusion reaction, which is very slow.

[0003] However, the current Nb core wire mostly adopts a cylindrical structure, and its contact area with the bronze matrix wrapped on the outside is limited, resulting in Sn and Nb taking a long time to fully react to form the Nb3Sn superconducting phase. Summary of the Invention

[0004] The embodiments of the present application provide a bronze-process niobium-tin superconducting wire preparation method and a superconducting wire, which are used to solve the problem of long reaction time between the cylindrical Nb core wire and the bronze matrix in the prior art.

[0005] On the one hand, the embodiments of the present application provide a method for preparing a niobium-tin superconducting wire by a bronze method, comprising:

[0006] The bronze rod is placed in the Nb tube, and the Nb tube is placed in the bronze tube, and then rotary forging, drawing and annealing are performed to prepare a bronze / Nb single core rod;

[0007] Multiple bronze / Nb single core rods are bundled in a hexagonal close-packed manner, coated with a barrier layer, and then placed in a copper tube to form the final billet;

[0008] The final billet is sequentially extruded, drawn and annealed to obtain a bronze-method niobium-tin superconducting wire.

[0009] On the other hand, an embodiment of the present application further provides a bronze-process niobium-tin superconducting wire, which is prepared using the above-mentioned method.

[0010] The bronze-process niobium-tin superconducting wire preparation method and superconducting wire in this application have the following advantages:

[0011] The shape of the Nb core wire is a circular tube, which increases the contact area between the bronze matrix and Nb, which is beneficial to the reaction between Sn and Nb during heat treatment, and the heat treatment time can be shortened by more than 20%. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0013] FIG1 is a schematic structural diagram of a bronze / Nb single core rod provided in an embodiment of the present application;

[0014] FIG2 is a schematic diagram of the structure of a superconducting wire provided in an embodiment of the present application.

[0015] Description of the accompanying drawings: 1-bronze tube, 2-bronze rod, 3-Nb tube, 4-copper tube, 5-barrier layer, 6-bronze / Nb single core rod. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0017] The present invention provides a method for preparing a niobium-tin superconducting wire by a bronze method, the method comprising the following steps:

[0018] S100, the bronze rod 2 is placed in the Nb tube 3, and the Nb tube 3 is placed in the bronze tube 1, and the bronze / Nb single core rod 6 is prepared after rotary forging, drawing and annealing.

[0019] For example, the outside of the Nb tube 3 is a bronze tube 1, and the inside is filled with a bronze rod 2. The material of the Nb tube 3 is Nb element or Nb alloy, such as NbTi, NbTa, etc. The dimensional accuracy of the Nb tube 3 should meet ±0.03mm, the surface roughness Ra should be less than or equal to 0.8μm, and the yield strength should be greater than 80MPa. When processing the bronze tube 1 filled with the Nb tube 3, when the diameter of the bronze tube 1 is greater than or equal to 15mm, a rotary forging method is adopted, and the deformation amount each time is greater than or equal to 30%. When the diameter of the bronze tube 1 is less than 15mm, a drawing method is adopted, and the deformation amount each time is greater than or equal to 30%. In the bronze / Nb single core rod 6 with an annular Nb core wire, the volume ratio of bronze to Nb is 1.0~5.0. The structure of the prepared bronze / Nb single core rod 6 is shown in Figure 1.

[0020] S110 , a plurality of bronze / Nb single core rods 6 are bundled in a hexagonal close-packed manner, coated with a barrier layer 5 on the outside, and then loaded into a copper tube 4 to form a final billet.

[0021] For example, the barrier layer 5 is made of Nb or Ta. In the final billet, the ratio of the sum of the radial cross-sectional areas of the bundled bronze / Nb single core rod 6 and the barrier layer 5 to the radial cross-sectional area of ​​the copper tube 4 is 1.0-4.0.

[0022] S120, sequentially extruding, drawing and intermediate annealing the final billet to obtain a bronze-method niobium-tin superconducting wire.

[0023] The embodiment of the present application further provides a bronze-process niobium-tin superconducting wire, which is prepared by the above-mentioned method.

[0024] 1. Place a Nb tube with a dimensional deviation of +0.03mm, a surface roughness of 0.8μm, and a yield strength of 95MPa into a bronze tube, and then install a bronze rod into the Nb tube. For diameters above 15mm, a rotary forging method with a single deformation of 30% is used, followed by a drawing method with a single deformation of 35% to obtain a bronze / Nb single-core rod with a ring-shaped Nb core wire, where the volume ratio of bronze to Nb is 1.0.

[0025] Hundreds of bronze / Nb single-core rods are bundled in a hexagonal close-packed pattern, coated with a Nb barrier layer, and then loaded into an oxygen-free copper tube to produce the final billet. The ratio of the combined cross-sectional area of ​​the bronze / Nb single-core rods and the Nb barrier layer to the cross-sectional area of ​​the oxygen-free copper tube is 1.0. The final billet is heated, extruded, drawn, and annealed to produce a bronze-processed Nb3Sn superconducting wire. Example

[0026] The method for preparing a niobium-tin superconducting wire using a bronze method provided in this application comprises the following steps:

[0027] 1. Place a Nb2Ti tube with a dimensional deviation of +0.01mm, a surface roughness of 0.8μm, and a yield strength of 82MPa into a bronze tube, and then install the bronze rod into the NbTi tube. For diameters above 15mm, a single-step swaging process with a deformation of 35% is used, followed by a single-step drawing process with a deformation of 30% to obtain a bronze / NbTi single-core rod with a ring-shaped NbTi core wire. The volume ratio of bronze to NbTi is 3.0.

[0028] Hundreds of bronze / NbTi single-core rods are bundled in a hexagonal close-packed pattern, coated with a Ta barrier layer, and then placed into an oxygen-free copper tube to produce the final billet. The ratio of the combined cross-sectional area of ​​the bronze / NbTi single-core rods and the Ta barrier layer to the cross-sectional area of ​​the oxygen-free copper tube is 2.0. The final billet is heated, extruded, drawn, and annealed to produce a bronze-processed Nb3Sn superconducting wire. Example

[0029] The method for preparing a niobium-tin superconducting wire using a bronze method provided in this application comprises the following steps:

[0030] 1. A Nb tube with a dimensional deviation of -0.03 mm, a surface roughness of 0.8 μm Ra, and a yield strength of 88 MPa was placed in a bronze tube, which was then loaded into a Nb1.5Ta tube. For diameters above 15 mm, a rotary swaging process with a single deformation of 33% was used, followed by a drawing process with a single deformation of 38% to obtain a bronze / NbTa single-core rod with an annular NbTa core wire. The volume ratio of bronze to NbTa was 5.0.

[0031] Hundreds of bronze / NbTa single-core rods are bundled in a hexagonal close-packed pattern, coated with a barrier layer of Nb, and then loaded into an oxygen-free copper tube to produce the final billet. The ratio of the combined cross-sectional area of ​​the bronze / NbTa single-core rods and the barrier layer to the cross-sectional area of ​​the oxygen-free copper tube is 4.0. The final billet is heated, extruded, drawn, and annealed to produce bronze-processed Nb3Sn superconducting wire.

[0032] Verification experiment

[0033] Comparing the bronze-process Nb3Sn superconducting wires obtained using the methods of Examples 1 to 3 of the present application with those not prepared using the present method, the Nb core of the bronze-process Nb3Sn superconducting wires prepared in Examples 1 to 3 of the present application completely reacted to form the Nb3Sn phase after a 75-hour heat treatment at 650°C. However, after a 100-hour heat treatment at 650°C, a small amount of Nb core remained in the center of the Nb3Sn superconducting wire not prepared using the present method. This demonstrates that the present method can effectively shorten the heat treatment time.

[0034] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0035] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A method for preparing a bronze-based niobium-tin superconducting wire, characterized in that: include: The bronze rod (2) is placed in a Nb tube (3), and the Nb tube (3) is placed in a bronze tube (1), and after rotary forging, drawing and annealing, a bronze / Nb single core rod (6) is prepared; A plurality of the bronze / Nb single core rods (6) are bundled in a hexagonal close-packed manner, coated with a barrier layer (5) on the outside, and then loaded into a copper tube (4) to form a final blank; The final billet is sequentially extruded, drawn and annealed to obtain a bronze-based niobium-tin superconducting wire.

2. The method for preparing a bronze-based niobium-tin superconducting wire according to claim 1, characterized in that: In the bronze / Nb single core rod (6), the volume ratio of bronze to Nb is 1.0-5.0, and the Nb core wire in the bronze / Nb single core rod (6) is ring-shaped.

3. The method for preparing a bronze-based niobium-tin superconducting wire according to claim 1, characterized in that: The material of the Nb tube (3) is single substance Nb or Nb alloy, the dimensional accuracy of the Nb tube (3) satisfies ±0.03 mm, the surface roughness Ra is less than or equal to 0.8 μm, and the yield strength is greater than 80 MPa.

4. The method for preparing a bronze-based niobium-tin superconducting wire according to claim 1, characterized in that: When processing the bronze tube (1) filled with the Nb tube (3), when the diameter of the bronze tube (1) is greater than or equal to 15 mm, a rotary forging method is used, and the deformation amount each time is greater than or equal to 30%; when the diameter of the bronze tube (1) is less than 15 mm, a drawing method is used, and the deformation amount each time is greater than or equal to 30%.

5. The method for preparing a bronze-based niobium-tin superconducting wire according to claim 1, characterized in that: The ratio of the sum of the radial cross-sectional areas of the bronze / Nb single core rod (6) and the barrier layer (5) to the radial cross-sectional area of ​​the copper tube (4) is 1.0 to 4.

0.

6. A bronze-process niobium-tin superconducting wire, characterized in that: The bronze-process niobium-tin superconducting wire is prepared by the method described in any one of claims 1-5.

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