Bronze method niobium three tin superconducting wire and its preparation method and assembly structure

Abstract

The application belongs to the technical field of superconducting wires, and relates to a bronze method Nb3Sn superconducting wire, a preparation method thereof and an assembly structure. The application provides a preparation method of the bronze method Nb3Sn superconducting wire, which comprises the following steps: obtaining an assembly structure through one-time assembly, wherein the assembly structure comprises a drilled bronze ingot, the drilled bronze ingot is provided with a plurality of drilled holes filled with Nb rods, and the drilled bronze ingot is sequentially arranged in a barrier layer and a stable matrix; and the assembly structure is subjected to extrusion, multi-pass drawing and annealing to obtain the Nb3Sn superconducting wire. The application obtains a composite rod with uniform core wires through one-time assembly and extrusion forming, and the composite rod is used for preparing the Nb3Sn superconducting wire by the bronze method. The application solves the technical problems of the bronze method for preparing the Nb3Sn superconducting wire, such as the need for two-time assembly, more production flow procedures and a longer preparation period.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of superconducting wires, and relates to a bronze method Nb3Sn superconducting wire, a preparation method thereof and an assembly structure. BACKGROUND

[0002] Nb3Sn superconducting wires are widely used in many fields such as particle accelerators, nuclear fusion experimental reactors and nuclear magnetic resonance spectrometers due to their high critical current density under high field conditions of more than 10T. The bronze method is a key technology for preparing Nb3Sn superconducting wires. Bronze method Nb3Sn superconducting wires have excellent current-carrying capacity and good mechanical properties, and become the main choice for preparing high-field magnets.

[0003] At present, the preparation method of bronze method Nb3Sn superconducting wires is usually divided into two times of composite assembly. The first time is to insert the Nb rod into the bronze matrix, and after extrusion and multi-pass drawing and annealing, the sub-element is obtained. The second time is to assemble the plurality of sub-elements and the barrier layer into the oxygen-free copper tube, and then after extrusion and multi-pass drawing and annealing, the bronze method Nb3Sn superconducting wire is obtained. The preparation process is two times of composite assembly, and the production process is relatively complicated and the preparation period is relatively long. SUMMARY

[0004] The technical problem to be solved by the present application is the need for two times of assembly, more production process procedures and longer preparation period in the preparation of bronze method Nb3Sn superconducting wires. To this end, the present application provides a bronze method Nb3Sn superconducting wire, a preparation method thereof and an assembly structure to solve this need in the art.

[0005] In one aspect, the present application relates to a preparation method of a bronze method Nb3Sn superconducting wire, comprising:

[0006] obtaining an assembly structure by one-time assembly, wherein the assembly structure comprises: a drilled bronze ingot, the drilled bronze ingot has a plurality of drilled holes filled with Nb rods, and the drilled bronze ingot is sequentially arranged in a barrier layer and a stable matrix;

[0007] obtaining a Nb3Sn superconducting wire by extruding, multi-pass drawing and annealing the assembly structure.

[0008] Further, in the preparation method of the bronze method Nb3Sn superconducting wire provided by the present application, the material of the barrier layer is Nb.

[0009] Further, in the preparation method of the bronze method Nb3Sn superconducting wire provided by the present application, the material of the stable matrix is oxygen-free copper.

[0010] Further, in the preparation method of bronze Nb3Sn superconducting wire provided by the application, the specification of the drilled bronze ingot is Φ100-300 mm, and the length is 300-1000 mm.

[0011] The number of the drilled holes in the drilled bronze ingot is 15-100, and the diameter of the through holes is Φ8-35 mm.

[0012] Further, in the preparation method of bronze Nb3Sn superconducting wire provided by the application, the extrusion mode is hydrostatic extrusion, the extrusion speed of the hydrostatic extrusion is 5-40 mm / s, and the extrusion ratio is 7-18.

[0013] Further, in the preparation method of bronze Nb3Sn superconducting wire provided by the application, the pass processing rate of the multi-pass drawing is 10-30%, and the drawing speed is 5-30 m / min.

[0014] Further, in the preparation method of bronze Nb3Sn superconducting wire provided by the application, the annealing mode is induction annealing, and the parameters of the induction annealing are that the annealing temperature is 300-600 ℃, and the annealing time is 10-30 min.

[0015] On the other hand, the application relates to a bronze Nb3Sn superconducting wire prepared by the preparation method of bronze Nb3Sn superconducting wire.

[0016] On the other hand, the application relates to an assembly structure for preparing bronze Nb3Sn superconducting wire, which comprises a drilled bronze ingot provided with a plurality of drilled holes loaded with Nb rods, and the drilled bronze ingot is sequentially loaded in a barrier layer and a stable matrix.

[0017] Further, in the assembly structure for preparing bronze Nb3Sn superconducting wire provided by the application, the material of the barrier layer is Nb, and the material of the stable matrix is oxygen-free copper.

[0018] Compared with the prior art, the technical scheme provided by the application has at least the following beneficial effects or advantages:

[0019] The application combines one-time assembly and hydrostatic extrusion forming, replaces two-time composite assembly, improves the uniformity of core wire deformation, saves the preparation of sub-components and the two-time assembly process, shortens the preparation period of the wire, and improves the yield of the product. The application further optimizes the induction heating mode of the annealing mode, greatly saves the production time, and shortens the preparation period of the wire. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0021] Figure 1 It is a cross-sectional structure schematic diagram of the assembly structure of the 19-core Nb3Sn superconducting wire.

[0022] Figure 2 It is a cross-sectional structure schematic diagram of the assembly structure of the 37-core Nb3Sn superconducting wire.

[0023] Figure 3 It is a cross-sectional structure schematic diagram of the assembly structure of the 91-core Nb3Sn superconducting wire.

[0024] Explanation of reference numerals: 1, oxygen-free copper tube; 2, Nb tube; 3, drilled bronze ingot; 4, Nb rod. DETAILED DESCRIPTION

[0025] The technical solutions of the present application will be described below in combination with embodiments, but the present application is not limited to the following embodiments. The experimental methods and detection methods described in each embodiment are all conventional methods unless otherwise specified; and the reagents and materials described are all commercially available unless otherwise specified. The % in the following examples is the mass percentage unless otherwise specified. The ratio in the following examples is the mass ratio unless otherwise specified.

[0026] In the following embodiments, the bronze ingot raw material is a Cu-Sn alloy with Sn content of 13-16wt.%, and the specification is Φ100-300mm and the length is 300-1000mm. The number of drilled holes is 15-100, and the diameter of the through holes is Φ8-35mm.

[0027] The present application provides a preparation method of an internal tin method Nb3Sn superconducting wire, comprising the following steps:

[0028] Step 1, select a bronze ingot as a substrate, drill a plurality of through holes along the length direction by using a deep hole drill to obtain a drilled bronze ingot.

[0029] Step 2, clean the drilled bronze ingot 3, Nb rod 4, Nb tube 2 (as a barrier layer) and oxygen-free copper tube 1, and then assemble after cleaning: insert the Nb rod 4 into the drilled bronze ingot 3, and together with the Nb tube 2, put them into the oxygen-free copper tube 1. Then cover the oxygen-free copper cover on both ends and perform electron beam welding to obtain a composite billet to be extruded.

[0030] Step 3: After heating and holding the composite billet obtained in Step 2, perform hydrostatic extrusion to obtain composite rods. The heating temperature is 300~700℃, the holding time is 60~240min, the extrusion speed is 5~40mm / s, and the extrusion ratio is 7~18.

[0031] Step 4: After multiple drawing passes and intermediate annealing, the composite rod obtained in Step 3 is subjected to Nb3Sn superconducting wire. The annealing method is induction annealing, with an annealing temperature of 300~600℃ and an annealing time of 10min~30min. The drawing pass rate is 10~30%, and the drawing speed is 5~30m / min.

[0032] Example 1

[0033] A bronze ingot with dimensions of Φ110mm and a length of 500mm was selected as the substrate. Nineteen through holes were drilled along the length using deep-hole drilling, arranged in three layers: a central layer of 1 through hole, a second outermost layer of 6 through holes, and an outermost layer of 12 through holes. The diameter of each through hole was Φ12mm, and the spacing between each layer was 8.5mm. The drilled bronze ingot 3, Nb rod 4, Nb tube 2 (as a barrier layer), and oxygen-free copper tube 1 were cleaned and then assembled: Nb rod 4 was inserted into the drilled bronze ingot 3 and, together with Nb tube 2, was inserted into the oxygen-free copper tube 1. The cross-sectional structure is shown below. Figure 1 As shown. Then, oxygen-free copper caps were added to both ends and electron beam welding was performed to obtain a composite billet with an outer diameter of Φ210mm. The composite billet was heated to 510℃ and held for 60 minutes before hydrostatic extrusion to obtain a Φ65mm composite rod. The extrusion speed was 25mm / s, and the extrusion ratio was 10.4. The extruded Φ65mm composite rod was subjected to multiple drawing passes and induction annealing at 400℃ for 10 minutes. The processing rate per drawing pass was 20%, and the drawing speed was 10m / min, resulting in a Nb3Sn superconducting wire with a final size of Φ0.72mm.

[0034] Comparing the two composite assemblies, the first involves inserting Nb rods into a bronze matrix, followed by extrusion, multiple drawing passes, and annealing to obtain subcomponents. The second involves bundling multiple subcomponents and a barrier layer together into an oxygen-free copper tube, followed by extrusion, multiple drawing passes, and annealing to obtain bronze-based Nb3Sn superconducting wire. The only difference is the two-stage assembly; the yield of the Nb3Sn superconducting wire provided in this embodiment is increased from 74.7% to 90.2%, and the production cycle is shortened from 190 hours to 95 hours.

[0035] Example 2

[0036] A bronze ingot was selected as the base material. The ingot's dimensions were Φ162mm and length 600mm. 37 through holes were drilled along the length using deep-hole drilling. These through holes were arranged in four layers, with one in the center, six in the center, twelve in the center, and eighteen in the outermost layer. The diameter of each through hole was Φ12mm, and the spacing between each layer was 10mm. The drilled bronze ingot (3), Nb rod (4), Nb tube (2) (as a barrier layer), and oxygen-free copper tube (1) were then cleaned and assembled. The Nb rod (4) was inserted into the drilled bronze ingot (3), and together with the Nb tube (2), it was inserted into the oxygen-free copper tube (1). The cross-sectional structure is shown below. Figure 2 As shown. Then, oxygen-free copper caps were added to both ends and electron beam welding was performed to obtain a composite billet with an outer diameter of Φ261mm. The composite billet was heated to 560℃ and held for 90 minutes before extrusion to obtain a composite rod with a diameter of Φ80mm. The extrusion speed was 20mm / s, and the extrusion ratio was 10.6. The extruded Φ80mm composite rod was subjected to multiple drawing passes and induction annealing at a temperature of 440℃ for 15 minutes. The processing rate per drawing pass was 25%, and the drawing speed was 15m / min, resulting in a Nb3Sn superconducting wire with a final size of Φ0.82mm.

[0037] Comparing the two composite assemblies, the first involves inserting Nb rods into a bronze matrix, followed by extrusion, multiple drawing passes, and annealing to obtain subcomponents. The second involves bundling multiple subcomponents and a barrier layer together into an oxygen-free copper tube, followed by extrusion, multiple drawing passes, and annealing to obtain bronze-based Nb3Sn superconducting wire. The only difference is the two-stage assembly; the yield of the Nb3Sn superconducting wire provided in this embodiment is increased from 71.3% to 89.7%, and the production cycle is shortened from 200 hours to 100 hours.

[0038] Example 3

[0039] A bronze ingot with dimensions of Φ234mm and a length of 550mm was selected as the substrate. Ninety-one through holes were drilled along the length using deep-hole drilling, arranged in six layers: center (1 hole), then six, twelve, eighteen, twenty-four, and finally an outermost layer of thirty. The diameter of each through hole was Φ12.5mm, and the spacing between layers was 8mm. The drilled bronze ingot (3), Nb rod (4), Nb tube (2 as a barrier layer), and oxygen-free copper tube (1) were then cleaned and assembled. The Nb rod (4) was inserted into the drilled bronze ingot (3), and together with the Nb tube (2), it was placed into the oxygen-free copper tube (1). The cross-sectional structure is shown below. Figure 3As shown. Then, oxygen-free copper caps were added to both ends and electron beam welding was performed to obtain a composite billet with an outer diameter of Φ318mm. The composite billet was heated to 600℃ and held for 120min before extrusion to obtain a Φ92mm composite rod. The extrusion speed was 17mm / s, and the extrusion ratio was 11.9. The extruded Φ92mm composite rod was subjected to multiple drawing passes and induction annealing at a temperature of 460℃ for 15min. The processing rate per drawing pass was 25%, and the drawing speed was 15m / min, resulting in a final Nb3Sn superconducting wire with a diameter of Φ1.12mm.

[0040] Comparing the two composite assemblies, the first involves inserting Nb rods into a bronze matrix, followed by extrusion, multiple drawing passes, and annealing to obtain subcomponents. The second involves bundling multiple subcomponents and a barrier layer together into an oxygen-free copper tube, followed by extrusion, multiple drawing passes, and annealing to obtain bronze-based Nb3Sn superconducting wire. The only difference is the two-stage assembly; the yield of the Nb3Sn superconducting wire provided in this embodiment is increased from 72.5% to 87.9%, and the production cycle is shortened from 210 hours to 110 hours.

[0041] As described above, the basic principles, main features, and advantages of the present invention have been well described. The above embodiments and specifications are merely descriptions of preferred embodiments of the present invention, and the present invention is not limited to the above embodiments. Various changes and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit and scope of the present invention should fall within the protection scope defined by the present invention.

Claims

1. A method for improving the yield and shortening the production cycle of bronze-based niobium-tin superconducting wires, characterized in that, include: A single assembly yields an assembly structure, which directly forms the final wire structure without the need for secondary bundled sub-components. The assembly structure includes: a drilled bronze ingot having multiple drill holes containing Nb rods, which is sequentially mounted in a barrier layer and a stabilizing matrix; the assembly structure is then subjected to extrusion, multiple drawing passes, and annealing to produce a niobium-tin superconducting wire. The barrier layer is made of Nb, and the stabilizing substrate is made of oxygen-free copper. The extrusion method is hydrostatic extrusion, and the extrusion speed of the hydrostatic extrusion is 5~40mm / s, and the extrusion ratio is 7~18. The drilled bronze ingot has a diameter of Φ100~300mm and a length of 300~1000mm; The number of holes in the drilled bronze ingot is 15 to 100, and the diameter of the through hole is Φ8 to 35mm.

2. The method for preparing bronze-based niobium-tin superconducting wire according to claim 1, characterized in that, The pass rate of the multi-pass drawing is 10-30%, and the drawing speed is 5-30 m / min.

3. The method for preparing bronze-based niobium-tin superconducting wire according to claim 1, characterized in that, The annealing method is induction annealing, and the parameters of the induction annealing are annealing temperature of 300~600℃ and annealing time of 10~30min.

4. A niobium-tin superconducting wire, characterized in that, It is prepared by the method of bronze method for preparing niobium-tin superconducting wire as described in any one of claims 1 to 3.

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