Bronze method niobium-tin superconducting wire and preparation method and assembly structure thereof

Abstract

The invention belongs to the technical field of superconducting wires, and relates to a bronze method niobium-tin superconducting wire and a preparation method and an assembly structure thereof. The invention provides a preparation method of a niobium-tin superconducting wire by a bronze method, which comprises the following steps: an assembly structure is obtained by one-time assembly, 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 carrying out extrusion, multi-pass drawing and annealing on the assembly structure to obtain the Nb3Sn superconducting wire. The composite bar with uniform core wires is prepared through one-time assembly and extrusion forming, and is used for preparing the Nb3Sn superconducting wire by a bronze method. The method solves the technical problems that secondary assembly is needed, the number of production procedures is large, and the preparation period is long when the Ni3Sn superconducting wire is prepared through a bronze method.

Description

Technical Field

[0001] The invention belongs to the technical field of superconducting wires, and relates to a bronze-process niobium-tin superconducting wire and a preparation method and an assembly structure thereof. Background Art

[0002] Niobium-tin superconducting wire (Nb3Sn superconducting wire) is widely used in many fields such as particle accelerators, nuclear fusion experimental reactors and nuclear magnetic resonance spectrometers due to its high critical current density under high field conditions above 10 T. Among them, the bronze method is a key technology for preparing Nb3Sn superconducting wire. The bronze method Nb3Sn superconducting wire has excellent current carrying capacity and good mechanical properties, making it the main choice for preparing high-field magnets.

[0003] At present, the preparation method of bronze-process Nb3Sn superconducting wire is usually divided into two composite assemblies. The first is to insert the Nb rod into the bronze matrix, and obtain subcomponents after extrusion, multiple drawing and annealing. The second is to load multiple subcomponents and barrier layers into an oxygen-free copper tube, and then obtain bronze-process Nb3Sn superconducting wire after extrusion, multiple drawing and annealing. The preparation process goes through two composite assemblies, the production process is relatively complicated and the preparation cycle is long. Summary of the invention

[0004] The purpose of the present invention is to solve the technical problems that the bronze method for preparing niobium-tin superconducting wires requires secondary assembly, has many production process procedures and a long preparation cycle. To this end, the present invention provides a bronze method niobium-tin superconducting wire and its preparation method and assembly structure to solve this need in the art.

[0005] In one aspect, the present invention relates to a method for preparing a bronze-process niobium-tin superconducting wire, comprising: The assembled structure is obtained by assembling once, and the assembled structure comprises: a drilled bronze ingot, the drilled bronze ingot having a plurality of drilled holes equipped with Nb rods, the drilled bronze ingot being sequentially installed in the barrier layer and the stabilizing matrix; The assembled structure is subjected to extrusion, multi-pass drawing and annealing to obtain a niobium-tin superconducting wire.

[0006] Furthermore, in the method for preparing the bronze-process niobium-tin superconducting wire provided by the present invention, the material of the barrier layer is Nb.

[0007] Furthermore, in the method for preparing the bronze-process niobium-tin superconducting wire provided by the present invention, the material of the stable matrix is ​​oxygen-free copper.

[0008] Furthermore, in the method for preparing the bronze-process niobium-tin superconducting wire provided by the present invention, the specification of the drilled bronze ingot is Φ100~300mm, and the length is 300~1000mm; The number of holes drilled in the drilled bronze ingot is 15 to 100, and the diameter of the through holes is Φ8 to 35 mm.

[0009] Furthermore, in the preparation method of the bronze-process niobium-tin superconducting wire provided by the present invention, the extrusion method is hydrostatic extrusion, the extrusion speed of the hydrostatic extrusion is 5-40 mm / s, and the extrusion ratio is 7-18.

[0010] Furthermore, in the method for preparing the bronze-process niobium-tin superconducting wire provided by the present invention, the processing rate of the multi-pass drawing is 10-30%, and the drawing speed is 5-30 m / min.

[0011] Furthermore, in the preparation method of the bronze-process niobium-tin superconducting wire provided by the present invention, the annealing method is induction annealing, and the parameters of the induction annealing are annealing temperature of 300-600° C. and annealing time of 10-30 min.

[0012] On the other hand, the present invention relates to a niobium-tin superconducting wire, which is prepared by the preparation method of the niobium-tin superconducting wire by the bronze process.

[0013] On the other hand, the present invention relates to an assembly structure for preparing niobium-tin superconducting wire by bronze method, the assembly structure comprising: a drilled bronze ingot having a plurality of drilled holes equipped with Nb rods, the drilled bronze ingot being sequentially installed in a barrier layer and a stabilizing matrix.

[0014] Furthermore, in the assembly structure for preparing niobium-tin superconducting wire by bronze process provided by the present invention, the material of the barrier layer is Nb, and the material of the stabilizing matrix is ​​oxygen-free copper.

[0015] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages: The present invention combines one-time assembly and hydrostatic extrusion molding to replace secondary composite assembly, improves the uniformity of core wire deformation, eliminates the preparation of subcomponents and secondary assembly process, shortens the preparation cycle of wires, and improves the yield rate of products. The present invention further optimizes the induction heating method in combination with the annealing method, greatly saving production time and shortening the preparation cycle of wires. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1This is a schematic diagram of the cross-sectional structure of the assembly structure of 19-core niobium-tin superconducting wires.

[0018] Figure 2 This is a schematic diagram of the cross-sectional structure of the assembly structure of 37-core niobium-tin superconducting wires.

[0019] Figure 3 This is a schematic diagram of the cross-sectional structure of the assembly structure of 91-core niobium-tin superconducting wires.

[0020] Explanation of the accompanying figures: 1. oxygen-free copper tube; 2. Nb tube; 3. drilled bronze ingot; 4. Nb rod. DETAILED DESCRIPTION

[0021] The technical scheme of the present invention is described below in conjunction with the embodiments, but the present invention is not limited to the following embodiments. The experimental methods and detection methods described in each embodiment are conventional methods unless otherwise specified; the reagents and materials can be purchased on the market unless otherwise specified. The % in the following embodiments, unless otherwise specified, are all mass percentages. The ratios in the following embodiments, unless otherwise specified, are all mass ratios.

[0022] In the following examples, the bronze ingot raw material is a Cu-Sn alloy with a Sn content of 13-16 wt.%, a size of Φ100-300 mm, a length of 300-1000 mm, a number of holes drilled of 15-100, and a through hole diameter of Φ8-35 mm.

[0023] The present invention provides a method for preparing a niobium-tin superconducting wire by an internal tin method, comprising the following steps: Step 1: Select a bronze ingot as a substrate, and use a deep hole drilling method to drill a number of through holes along the length direction to obtain a drilled bronze ingot.

[0024] Step 2: The drilled bronze ingot 3, Nb rod 4, Nb tube 2 (as a barrier layer) and oxygen-free copper tube 1 are cleaned and assembled after cleaning: the Nb rod 4 is inserted into the drilled bronze ingot 3, and is loaded into the oxygen-free copper tube 1 together with the Nb tube 2. Then, oxygen-free copper caps are added to both ends and electron beam welding is performed to obtain a composite billet to be extruded.

[0025] Step 3, heating and keeping the composite blank obtained in step 2, and then performing hydrostatic extrusion to obtain a composite rod. The heating temperature is 300-700°C, the holding time is 60-240 minutes, the extrusion speed is 5-40 mm / s, and the extrusion ratio is 7-18.

[0026] Step 4, after multiple drawing and intermediate annealing of the composite rod obtained in step 3, Nb3Sn superconducting wire is obtained. The annealing method is induction annealing, the annealing temperature is 300-600°C, and the annealing time is 10min-30min. The drawing process rate is 10-30%, and the drawing speed is 5-30m / min.

[0027] Example 1 A bronze ingot was selected as the substrate. The specification of the bronze ingot was Φ110 mm and the length was 500 mm. 19 through holes were drilled along the length direction by deep hole drilling. The through holes were 3 layers and arranged in the order of 1 in the center + 6 in the second outer layer + 12 in the outermost layer. The through hole diameter was Φ12 mm and the spacing between each layer was 8.5 mm. The drilled bronze ingot was obtained. The drilled bronze ingot 3, Nb rod 4, Nb tube 2 (as a barrier layer) and oxygen-free copper tube 1 were cleaned and assembled after cleaning: the Nb rod 4 was inserted into the drilled bronze ingot 3 and loaded into the oxygen-free copper tube 1 together with the Nb tube 2. The cross-sectional structure is as follows: Figure 1 As shown. Then, oxygen-free copper caps are added to both ends and electron beam welding is performed to obtain a composite billet with an outer diameter of Φ210mm. The composite billet is heated to 510℃ and kept warm for 60min for hydrostatic extrusion to obtain a Φ65mm composite rod. The extrusion speed is 25mm / s and the extrusion ratio is 10.4. The Φ65mm composite rod obtained by extrusion is subjected to multiple drawing and induction annealing. The annealing temperature is 400℃ and the annealing time is 10min. The processing rate of each stretching pass is 20%, and the stretching speed is 10m / min, to obtain a Nb3Sn superconducting wire with a final size of Φ0.72mm.

[0028] Comparing the two composite assemblies, the first one is to insert the Nb rod into the bronze matrix, and obtain the subcomponent after extrusion, multiple drawing and annealing, and the second one is to load multiple subcomponents and barrier layers into the oxygen-free copper tube, and then obtain the bronze method Nb3Sn superconducting wire after extrusion, multiple drawing and annealing. Only different from the secondary assembly, the yield rate of the Nb3Sn superconducting wire provided in this embodiment is increased from 74.7% to 90.2%, and the production cycle is shortened from 190h to 95h.

[0029] Example 2 A bronze ingot was selected as the substrate. The specification of the bronze ingot was Φ162mm and the length was 600mm. A deep hole drilling method was used to drill 37 through holes along the length direction. The through holes were 4 layers, arranged in the order of 1 in the center + 6 + 12 + 18 in the outermost layer. The through hole diameter was Φ12mm and the spacing between each layer was 10mm. The drilled bronze ingot was obtained. The drilled bronze ingot 3, Nb rod 4, Nb tube 2 (as a barrier layer) and oxygen-free copper tube 1 were cleaned and assembled after cleaning: the Nb rod 4 was inserted into the drilled bronze ingot 3, and was installed into the oxygen-free copper tube 1 together with the Nb tube 2. The cross-sectional structure is as follows: Figure 2As shown. Then, oxygen-free copper caps are added to both ends and electron beam welding is performed to obtain a composite billet with an outer diameter of Φ261mm. The composite billet is heated to 560°C and kept warm for 90 minutes for extrusion to obtain a Φ80mm composite rod. The extrusion speed is 20mm / s and the extrusion ratio is 10.6. The Φ80mm composite rod obtained by extrusion is subjected to multiple drawing and induction annealing. The annealing temperature is 440°C and the annealing time is 15min. The processing rate of each stretching pass is 25%, and the stretching speed is 15m / min, and a Nb3Sn superconducting wire with a final size of Φ0.82mm is obtained.

[0030] Comparing the two composite assemblies, the first one is to insert the Nb rod into the bronze matrix, and obtain the subcomponents after extrusion, multiple drawing and annealing, and the second one is to load multiple subcomponents and barrier layers into the oxygen-free copper tube, and then obtain the bronze method Nb3Sn superconducting wire after extrusion, multiple drawing and annealing. Only different from the secondary assembly, the yield rate of the Nb3Sn superconducting wire provided in this embodiment is increased from 71.3% to 89.7%, and the production cycle is shortened from 200h to 100h.

[0031] Example 3 A bronze ingot was selected as the substrate. The specification of the bronze ingot was Φ234mm and the length was 550mm. A deep hole drilling method was used to drill 91 through holes along the length direction. The through holes were 6 layers, arranged in the order of 1 in the center + 6 + 12 + 18 + 24 + 30 in the outermost layer. The through hole diameter was Φ12.5mm and the spacing between each layer was 8mm. The drilled bronze ingot was obtained. The drilled bronze ingot 3, Nb rod 4, Nb tube 2 (as a barrier layer) and oxygen-free copper tube 1 were cleaned and assembled after cleaning: the Nb rod 4 was inserted into the drilled bronze ingot 3, and was installed into the oxygen-free copper tube 1 together with the Nb tube 2. The cross-sectional structure is as follows: Figure 3 As shown. Then, oxygen-free copper caps are added to both ends and electron beam welding is performed to obtain a composite billet with an outer diameter of Φ318mm. The composite billet is heated to 600℃ and kept warm for 120min for extrusion to obtain a Φ92mm composite rod. The extrusion speed is 17mm / s and the extrusion ratio is 11.9. The Φ92mm composite rod obtained by extrusion is subjected to multiple drawing and induction annealing. The annealing temperature is 460℃ and the annealing time is 15min. The processing rate of each stretching pass is 25%, and the stretching speed is 15m / min, to obtain a Nb3Sn superconducting wire with a final size of Φ1.12mm.

[0032] Comparing the two composite assemblies, the first one is to insert the Nb rod into the bronze matrix, and obtain the subcomponents after extrusion, multiple drawing and annealing, and the second one is to load multiple subcomponents and barrier layers into the oxygen-free copper tube, and then obtain the bronze method Nb3Sn superconducting wire after extrusion, multiple drawing and annealing. Only different from the secondary 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 210h to 110h.

[0033] As described above, the basic principle, main features and advantages of the present invention are well described. The above embodiments and descriptions are only descriptions of the preferred implementation modes of the present invention, and the present invention is not limited by the above embodiments. Without departing from the spirit and scope of the present invention, various changes and improvements made by ordinary technicians in this field to the technical solution of the present invention should fall within the protection scope determined by the present invention.

Claims

1. A method for preparing a bronze-process niobium-tin superconducting wire, characterized in that: include: The assembled structure is obtained by assembling once, and the assembled structure comprises: a drilled bronze ingot, the drilled bronze ingot having a plurality of drilled holes equipped with Nb rods, the drilled bronze ingot being sequentially installed in the barrier layer and the stabilizing matrix; The assembled structure is subjected to extrusion, multi-pass drawing and annealing to obtain a niobium-tin superconducting wire.

2. The method for preparing the bronze-process niobium-tin superconducting wire according to claim 1, characterized in that: The material of the barrier layer is Nb.

3. The method for preparing the bronze-process niobium-tin superconducting wire according to claim 1, characterized in that: The material of the stable matrix is ​​oxygen-free copper.

4. The method for preparing the bronze-process niobium-tin superconducting wire according to claim 1, characterized in that: The specifications of the drilled bronze ingot are Φ100~300mm and the length is 300~1000mm; The number of holes drilled in the drilled bronze ingot is 15 to 100, and the diameter of the through holes is Φ8 to 35 mm.

5. The method for preparing bronze-process niobium-tin superconducting wire according to claim 1, characterized in that: The extrusion method is hydrostatic extrusion, the extrusion speed of the hydrostatic extrusion is 5-40 mm / s, and the extrusion ratio is 7-18.

6. The method for preparing bronze-process niobium-tin superconducting wire according to claim 1, characterized in that: The multi-pass drawing has a pass processing rate of 10-30% and a stretching speed of 5-30 m / min.

7. The method for preparing bronze-process 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° C. and annealing time of 10-30 min.

8. A niobium-tin superconducting wire, characterized in that: The method for preparing the bronze-process niobium-tin superconducting wire according to any one of claims 1 to 7 is adopted.

9. An assembly structure for preparing bronze-process niobium-tin superconducting wire, characterized in that: The assembly structure comprises a drilled bronze ingot having a plurality of drilled holes with Nb rods installed therein, and the drilled bronze ingot is sequentially installed in a barrier layer and a stabilizing matrix.

10. The assembly structure for preparing bronze-process niobium-tin superconducting wire according to claim 9, characterized in that: The material of the barrier layer is Nb, and the material of the stable matrix is ​​oxygen-free copper.

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