A method for preparing artificially pinned NbTi multi-core superconducting composite wire

Abstract

The invention discloses a method for preparing an artificially pinned NbTi multi-core superconducting composite wire, and relates to the technical field of superconducting material processing, comprising the following steps: combining Ti wire and NbTi wire and twisting them, cutting them to a fixed length and then loading them into an oxygen-free copper tube to obtain a NbTi / Ti / Cu core rod, loading them into an oxygen-free copper sleeve, and performing sealing welding to obtain a NbTi / Ti / Cu multi-core ingot blank, performing thermal diffusion treatment to obtain a NbTi / Ti / Cu artificially pinned ingot blank, performing hot extrusion to obtain a NbTi / Ti / Cu artificially pinned composite rod, drawing it to an aging heat treatment size, and performing aging heat treatment to obtain an artificially pinned NbTi multi-core superconducting composite wire. The present application reduces the difficulty of preparation while increasing the critical current density by twisting Ti wire and NbTi wire, combining thermal diffusion, hot extrusion, drawing and aging heat treatment.

Description

Technical Field

[0001] The present application relates to the technical field of superconducting material processing, and in particular to a method for preparing an artificially pinned NbTi multi-core superconducting composite wire. Background Art

[0002] NbTi superconducting wire is the most widely used superconducting material at present. It is mainly used in nuclear fusion experimental devices, MRI nuclear magnetic resonance imaging devices, particle accelerator devices, etc. However, there is a limit to the critical current density of NbTi superconducting wire under low field. This is because NbTi superconducting material uses α-Ti in NbTi alloy as the pinning center of superconducting material. The more pinning centers there are, the higher its critical current density is. However, since the precipitation amount of α-Ti precipitates in NbTi alloy is limited, the upper limit of α-Ti precipitation also limits the further improvement of the critical current density of conventional NbTi superconducting wire. In order to improve the critical current density of NbTi superconducting materials, other materials are currently added to NbTi alloy as artificial pinning centers to increase the number of pinning centers in the superconductor to achieve the effect of improving the critical current density of NbTi superconductors. Commonly used methods for preparing NbTi superconductors by artificial pinning include drilling method, rolling method, powder metallurgy method, etc.

[0003] In the prior art, Chinese patent CN116475263A discloses a method for preparing a distributed artificially pinned NbTi superconducting wire, by regularly drilling holes in the axial and radial directions of the NbTi ingot, the size and shape of the holes can be designed according to the performance requirements, and an axially and radially porous NbTi ingot is obtained. The pinning rod is then machined to obtain a pinning rod matching the aperture size, which is then assembled, welded, extruded, multi-pass drawn, and cut to size to obtain a NbTi / Cu single core rod with a high-density uniform pinning center. Finally, it is reassembled, welded, extruded, multi-pass drawn, and heat treated to finally obtain a NbTi / Cu composite wire with a distributed artificial pinning center.

[0004] However, although the above-mentioned prior art improves the critical current density by regularly drilling holes in the axial and radial directions of the NbTi ingot, its process is relatively complicated and the parameters involved are relatively cumbersome, and the preparation is difficult. Summary of the invention

[0005] The present application provides a method for preparing an artificially pinned NbTi multi-core superconducting composite wire, which is used to solve the problem that the existing technical process for preparing artificially pinned NbTi superconducting composite wire is relatively complex, the parameters involved are relatively complicated, and the preparation is difficult.

[0006] On the one hand, the present application provides a method for preparing an artificially pinned NbTi multi-core superconducting composite wire, comprising the following steps:

[0007] Step 1: Prepare Ti wire and NbTi wire.

[0008] Step 2: Combine and twist a plurality of the Ti wires and a plurality of the NbTi wires to obtain a NbTi / Ti multi-core wire.

[0009] Step three, cutting the NbTi / Ti multi-core wire into a fixed length and placing it into an oxygen-free copper tube to obtain a NbTi / Ti / Cu core rod.

[0010] Step 4: Place a plurality of the NbTi / Ti / Cu core rods into an oxygen-free copper sleeve and perform sealing welding to obtain a NbTi / Ti / Cu multi-core ingot.

[0011] Step five: thermally diffuse the NbTi / Ti / Cu multi-core ingot to obtain an artificially pinned NbTi / Ti / Cu ingot.

[0012] Step six, hot-extrude the NbTi / Ti / Cu artificially pinned ingot to obtain a NbTi / Ti / Cu artificially pinned composite rod.

[0013] Step seven, drawing the NbTi / Ti / Cu artificially pinned composite rod to an aging heat treatment size, and performing aging heat treatment several times to obtain an artificially pinned NbTi multi-core superconducting composite wire.

[0014] In a possible implementation, step one includes:

[0015] Copper tubes were respectively placed on the surfaces of the Ti rod and the NbTi rod to obtain Ti / Cu rods and NbTi / Cu rods.

[0016] The Ti / Cu rod and the NbTi / Cu rod are drawn respectively to obtain Ti / Cu wire and NbTi / Cu wire.

[0017] The Ti / Cu wire and the NbTi / Cu wire are respectively subjected to acid corrosion treatment to obtain the Ti wire and the NbTi wire.

[0018] In a possible implementation, in step 1, the diameters of the Ti rod and the NbTi rod are 10-20 mm, the inner hole diameter of the copper tube is 10.1-20.2 mm, the wall thickness is 1-4 mm, the diameters of the Ti / Cu wire and the NbTi / Cu wire are 1-2 mm, and the acid corrosion uses a HON3 solution with a mass fraction of 20%-40%.

[0019] In a possible implementation, in step 2, the combination adopts an interval distribution combination, and the diameter of the NbTi / Ti multi-core wire is 3-6 mm.

[0020] In a possible implementation, in step three, the length of the NbTi / Ti multi-core wire after being cut into fixed lengths is 300-500 mm, the inner hole diameter of the oxygen-free copper tube is 3.2-6.2 mm, the wall thickness is 1-2 mm, and the length is 300-500 mm.

[0021] In a possible implementation, in step 4, the inner hole diameter of the oxygen-free copper sleeve is 40-70 mm, the wall thickness is 5-10 mm, and the sealing is performed by vacuum electron beam sealing.

[0022] In a possible implementation, in step five, the temperature of the thermal diffusion treatment is 700-900° C., and the insulation time is 20-50 hours.

[0023] In a possible implementation, in step six, the temperature of the hot extrusion is 500-900° C., and the insulation time is 1-5 hours.

[0024] The method for preparing an artificially pinned NbTi multi-core superconducting composite wire in the present application has the following advantages:

[0025] By preparing Ti wires and NbTi wires, combining several Ti wires and several NbTi wires and twisting them, combining thermal diffusion, hot extrusion, drawing and aging heat treatment, we can finally obtain an artificially pinned NbTi multi-core superconducting composite wire, which improves the critical current density while reducing the difficulty of preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application 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 application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic flow chart of a method for preparing an artificially pinned NbTi multi-core superconducting composite wire provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0029] like Figure 1As shown, the embodiment of the present application provides a method for preparing an artificially pinned NbTi multi-core superconducting composite wire, comprising the following steps:

[0030] Step 1: Prepare Ti wire and NbTi wire.

[0031] Step 2: Combine and twist a plurality of the Ti wires and a plurality of the NbTi wires to obtain a NbTi / Ti multi-core wire.

[0032] Step three, cutting the NbTi / Ti multi-core wire into a fixed length and placing it into an oxygen-free copper tube to obtain a NbTi / Ti / Cu core rod.

[0033] Step 4: Place a plurality of the NbTi / Ti / Cu core rods into an oxygen-free copper sleeve and perform sealing welding to obtain a NbTi / Ti / Cu multi-core ingot.

[0034] Step five: thermally diffuse the NbTi / Ti / Cu multi-core ingot to obtain an artificially pinned NbTi / Ti / Cu ingot.

[0035] Step six, hot-extrude the NbTi / Ti / Cu artificially pinned ingot to obtain a NbTi / Ti / Cu artificially pinned composite rod.

[0036] Step seven, drawing the NbTi / Ti / Cu artificially pinned composite rod to an aging heat treatment size, and performing aging heat treatment several times to obtain an artificially pinned NbTi multi-core superconducting composite wire.

[0037] Exemplarily, step one includes:

[0038] Copper tubes were respectively placed on the surfaces of the Ti rod and the NbTi rod to obtain Ti / Cu rods and NbTi / Cu rods.

[0039] The Ti / Cu rod and the NbTi / Cu rod are drawn respectively to obtain Ti / Cu wire and NbTi / Cu wire.

[0040] The Ti / Cu wire and the NbTi / Cu wire are respectively subjected to acid corrosion treatment to obtain the Ti wire and the NbTi wire.

[0041] Embodiment 1:

[0042] Exemplarily, in step one, the diameter of the Ti rod and the NbTi rod is 10 mm, the inner hole diameter of the copper tube is 10.1 mm, the wall thickness is 1 mm, the diameter of the Ti / Cu wire and the NbTi / Cu wire is 1 mm, and the acid corrosion uses a HON3 solution with a mass fraction of 20%.

[0043] Exemplarily, in step 2, the combination adopts an interval distribution combination, and the diameter of the NbTi / Ti multi-core wire is 3 mm.

[0044] Specifically, in Example 1, 4 NbTi wires are combined with 3 Ti wires in a ratio of interval distribution, wherein 1 NbTi wire is located in the center, and 3 NbTi wires and 3 Ti wires are distributed at intervals on the outside. In other possible embodiments, NbTi wires and Ti wires can also be combined in other ratios and forms, as long as the interval distribution combination is satisfied, it should also fall within the protection scope of this application.

[0045] Exemplarily, in step three, the length of the NbTi / Ti multi-core wire after being cut to size is 300 mm, the inner hole diameter of the oxygen-free copper tube is 3.2 mm, the wall thickness is 1 mm, and the length is 300 mm.

[0046] Exemplarily, in step 4, the inner hole diameter of the oxygen-free copper sleeve is 40 mm, the wall thickness is 5 mm, and the sealing is performed by vacuum electron beam sealing.

[0047] Exemplarily, in step five, the temperature of the thermal diffusion treatment is 700° C., and the insulation time is 20 hours.

[0048] Exemplarily, in step six, the temperature of the hot extrusion is 500° C., and the insulation time is 1 hour.

[0049] Specifically, in Example 1, the critical current density of the artificially pinned NbTi multi-core superconducting composite wire finally obtained in step 7 is 7650A / mm 2 (2T).

[0050] Embodiment 2:

[0051] Exemplarily, in step one, the diameter of the Ti rod and the NbTi rod is 15 mm, the inner hole diameter of the copper tube is 15.15 mm, the wall thickness is 2.5 mm, the diameter of the Ti / Cu wire and the NbTi / Cu wire is 1.5 mm, and the acid corrosion uses a HON3 solution with a mass fraction of 30%.

[0052] Exemplarily, in step 2, the combination adopts an interval distribution combination, and the diameter of the NbTi / Ti multi-core wire is 4.5 mm.

[0053] Specifically, in Example 2, 4 NbTi wires are combined with 3 Ti wires in a ratio of interval distribution, wherein 1 NbTi wire is located in the center, and 3 NbTi wires and 3 Ti wires are distributed at intervals on the outside. In other possible embodiments, NbTi wires and Ti wires may be combined in other ratios and forms, and as long as the interval distribution combination is satisfied, it should also fall within the protection scope of the present application.

[0054] Exemplarily, in step three, the length of the NbTi / Ti multi-core wire after being cut to size is 400 mm, the inner hole diameter of the oxygen-free copper tube is 4.7 mm, the wall thickness is 1.5 mm, and the length is 400 mm.

[0055] Exemplarily, in step 4, the inner hole diameter of the oxygen-free copper sleeve is 55 mm, the wall thickness is 7.5 mm, and the sealing is performed by vacuum electron beam sealing.

[0056] Exemplarily, in step five, the temperature of the thermal diffusion treatment is 800° C., and the insulation time is 35 hours.

[0057] Exemplarily, in step six, the temperature of the hot extrusion is 700° C., and the insulation time is 3 hours.

[0058] Specifically, in Example 2, the critical current density of the artificially pinned NbTi multi-core superconducting composite wire finally obtained in step 7 is 8320A / mm 2 (2T).

[0059] Embodiment 3:

[0060] Exemplarily, in step one, the diameter of the Ti rod and the NbTi rod is 20 mm, the inner hole diameter of the copper tube is 20.2 mm, the wall thickness is 4 mm, the diameter of the Ti / Cu wire and the NbTi / Cu wire is 2 mm, and the acid corrosion uses a HON3 solution with a mass fraction of 40%.

[0061] Exemplarily, in step 2, the combination adopts an interval distribution combination, and the diameter of the NbTi / Ti multi-core wire is 6 mm.

[0062] Specifically, in Example 3, 4 NbTi wires are combined with 3 Ti wires in a ratio of interval distribution, wherein 1 NbTi wire is located in the center, and 3 NbTi wires and 3 Ti wires are distributed at intervals on the outside. In other possible embodiments, NbTi wires and Ti wires can also be combined in other ratios and forms, as long as the interval distribution combination is satisfied, it should also fall within the protection scope of this application.

[0063] Exemplarily, in step three, the length of the NbTi / Ti multi-core wire after being cut to size is 500 mm, the inner hole diameter of the oxygen-free copper tube is 6.2 mm, the wall thickness is 2 mm, and the length is 500 mm.

[0064] Exemplarily, in step 4, the inner hole diameter of the oxygen-free copper sleeve is 70 mm, the wall thickness is 10 mm, and the sealing is performed by vacuum electron beam sealing.

[0065] Exemplarily, in step five, the temperature of the thermal diffusion treatment is 900° C., and the insulation time is 50 hours.

[0066] Exemplarily, in step six, the temperature of the hot extrusion is 900° C., and the insulation time is 5 hours.

[0067] Specifically, in Example 3, the critical current density of the artificially pinned NbTi multi-core superconducting composite wire finally obtained in step 7 is 8500A / mm 2 (2T).

[0068] In the embodiment of the present application, Ti wires and NbTi wires are prepared, several Ti wires and several NbTi wires are combined and twisted, and thermal diffusion, hot extrusion, drawing and aging heat treatment are combined to finally obtain an artificially pinned NbTi multi-core superconducting composite wire, which reduces the difficulty of preparation while improving the critical current density.

[0069] Although the preferred embodiments of the present application have been described, those skilled in the art may make other 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 falling within the scope of the present application.

[0070] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for preparing an artificially pinned NbTi multi-core superconducting composite wire, characterized in that: The following steps are involved: Step 1, preparing Ti wire and NbTi wire; Step 2, combining a plurality of the Ti wires and a plurality of the NbTi wires and twisting them to obtain a NbTi / Ti multi-core wire; Step 3, cutting the NbTi / Ti multi-core wire into a fixed length and placing it into an oxygen-free copper tube to obtain a NbTi / Ti / Cu core rod; Step 4, placing a plurality of the NbTi / Ti / Cu core rods into an oxygen-free copper sleeve, and sealing and welding the sleeve to obtain a NbTi / Ti / Cu multi-core ingot; Step 5, performing thermal diffusion treatment on the NbTi / Ti / Cu multi-core ingot to obtain a NbTi / Ti / Cu artificially pinned ingot; Step six, hot extruding the NbTi / Ti / Cu artificially pinned ingot to obtain a NbTi / Ti / Cu artificially pinned composite rod; Step seven, drawing the NbTi / Ti / Cu artificially pinned composite rod to an aging heat treatment size, and performing aging heat treatment several times to obtain an artificially pinned NbTi multi-core superconducting composite wire.

2. The method for preparing an artificially pinned NbTi multi-core superconducting composite wire according to claim 1, characterized in that: Step one includes: Copper tubes are respectively placed on the surfaces of Ti rods and NbTi rods to obtain Ti / Cu rods and NbTi / Cu rods; Drawing the Ti / Cu rod and the NbTi / Cu rod respectively to obtain Ti / Cu wire and NbTi / Cu wire; The Ti / Cu wire and the NbTi / Cu wire are respectively subjected to acid corrosion treatment to obtain the Ti wire and the NbTi wire.

3. The method for preparing an artificially pinned NbTi multi-core superconducting composite wire according to claim 2, characterized in that: In step 1, the diameters of the Ti rod and the NbTi rod are 10-20 mm, the inner hole diameter of the copper tube is 10.1-20.2 mm, the wall thickness is 1-4 mm, the diameters of the Ti / Cu wire and the NbTi / Cu wire are 1-2 mm, and the acid corrosion adopts a HON3 solution with a mass fraction of 20%-40%.

4. The method for preparing an artificially pinned NbTi multi-core superconducting composite wire according to claim 1, characterized in that: In step 2, the combination adopts an interval distribution combination, and the diameter of the NbTi / Ti multi-core wire is 3-6 mm.

5. The method for preparing an artificially pinned NbTi multi-core superconducting composite wire according to claim 1, characterized in that: In step three, the length of the NbTi / Ti multi-core wire after being cut into fixed lengths is 300-500 mm, the inner hole diameter of the oxygen-free copper tube is 3.2-6.2 mm, the wall thickness is 1-2 mm, and the length is 300-500 mm.

6. The method for preparing an artificially pinned NbTi multi-core superconducting composite wire according to claim 1, characterized in that: In step 4, the inner hole diameter of the oxygen-free copper sleeve is 40-70 mm, the wall thickness is 5-10 mm, and the sealing is performed by vacuum electron beam sealing.

7. The method for preparing an artificially pinned NbTi multi-core superconducting composite wire according to claim 1, characterized in that: In step five, the temperature of the thermal diffusion treatment is 700-900° C., and the insulation time is 20-50 hours.

8. The method for preparing an artificially pinned NbTi multi-core superconducting composite wire according to claim 1, characterized in that: In step six, the temperature of the hot extrusion is 500-900° C., and the insulation time is 1-5 hours.

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