Niobium-titanium superconducting wire and preparation method and application thereof

Abstract

The invention provides a niobium-titanium superconducting wire and a preparation method and application thereof, and belongs to the technical field of superconducting materials. Copper is adopted as a wrapping material of the wire, heat dissipation is facilitated, in the repeated drawing process, the copper can reduce stress, and breakage during drawing is avoided; by adopting a repeated drawing process, the diameter of the niobium-titanium wire material can be reduced to a micron level, the continuity, uniformity and stability of the niobium-titanium large-bundle wire material in the niobium-titanium superconducting wire material are ensured, and the phenomena of cutoff and obstruction are not generated during superconducting electrification in a low-temperature state, so that the continuity and stability of superconducting performance are ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of superconducting materials, and in particular relates to a niobium-titanium superconducting wire and a preparation method and application thereof. Background Art

[0002] Niobium-titanium (Nb-Ti) alloy is widely used in superconducting cables and magnets because of its superconducting properties at ultra-low temperatures. At present, the preparation methods of niobium-titanium superconducting wires mainly include ingot preparation, direct wire drawing from niobium-titanium ingots, and high-purity copper dip-wrapping processes. However, the prepared niobium-titanium wires are relatively thick in diameter, and the wires are easily broken when the diameter of the drawn wires is less than 1 mm, which limits the length of the cables made from the wires. Therefore, how to prepare small-diameter niobium-titanium superconducting wires has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0003] The purpose of the present invention is to provide a niobium-titanium superconducting wire and a preparation method and application thereof. The diameter of the niobium-titanium superconducting wire prepared by the preparation method provided by the present invention can be reduced to 2-5 μm.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for preparing a niobium-titanium superconducting wire, comprising the following steps:

[0006] (1) drawing the niobium-titanium ingot to obtain a wire;

[0007] (2) bundling the wires obtained in step (1) to obtain bundled wires;

[0008] (3) copper-coating the bundled wire obtained in step (2) to obtain copper-coated wire;

[0009] (4) Repeat steps (1) to (3) until the diameter of the niobium-titanium superconducting wire reaches 2 to 5 μm, thereby obtaining the niobium-titanium superconducting wire.

[0010] Preferably, the method for preparing the niobium-titanium ingot in step (1) comprises:

[0011] The niobium bars / rods and the titanium bars / rods are bundled into bundles, smelted in an electric arc furnace and cast in turn to obtain niobium-titanium ingots.

[0012] Preferably, when the bundles are bundled, the titanium bars / rods are used as cores and the niobium bars / rods are used as wrappers.

[0013] Preferably, in the step (1), the mass of titanium in the niobium-titanium ingot is 47.5-48.5%, and the mass of niobium in the niobium-titanium ingot is 51.5-52.5%.

[0014] Preferably, the diameter of the wire in step (1) is 1.5 to 2.5 mm.

[0015] Preferably, the diameter of the wire is 2 mm.

[0016] Preferably, in step (3), the diameter of the copper-wrapped wire is at least 10 mm larger than the diameter of the bundled wire.

[0017] The present invention also provides a niobium-titanium superconducting wire prepared by the preparation method described in the above technical solution.

[0018] Preferably, the diameter of the niobium-titanium wire in the niobium-titanium superconducting wire is 2-5 μm.

[0019] The present invention also provides the application of the niobium-titanium superconducting wire material described in the above technical solution in electric cables.

[0020] The present invention provides a method for preparing a niobium-titanium superconducting wire, comprising the following steps: (1) drawing a niobium-titanium ingot to obtain a wire; (2) bundling the wire obtained in step (1) to obtain a bundle of wires; (3) wrapping the bundle of wires obtained in step (2) with copper to obtain a copper-wrapped wire; (4) repeating steps (1) to (3) until the diameter of the niobium-titanium wire in the niobium-titanium superconducting wire reaches 2 to 5 μm, thereby obtaining the niobium-titanium superconducting wire. The present invention uses copper as the wrapping material of the wire, which is conducive to heat dissipation. During repeated drawing, copper can reduce stress and avoid breakage during drawing; by using a repeated drawing process, the diameter of the niobium-titanium wire can be reduced to the micron level, thereby ensuring the continuity, uniformity and stability of the niobium-titanium large bundle of wires in the niobium-titanium superconducting wire, ensuring that no interruption and blocking phenomena occur when superconducting electricity is turned on at low temperature, thereby ensuring the continuity and stability of the superconducting performance. Experimental results show that the diameter of the niobium-titanium superconducting wire prepared by the preparation method provided by the present invention is 2 to 5 μm. DETAILED DESCRIPTION

[0021] The present invention provides a method for preparing a niobium-titanium superconducting wire, comprising the following steps:

[0022] (1) drawing the niobium-titanium ingot to obtain a wire;

[0023] (2) bundling the wires obtained in step (1) to obtain bundled wires;

[0024] (3) copper-coating the bundled wire obtained in step (2) to obtain copper-coated wire;

[0025] (4) Repeat steps (1) to (3) until the diameter of the niobium-titanium superconducting wire reaches 2 to 5 μm, thereby obtaining the niobium-titanium superconducting wire.

[0026] The present invention has no particular limitation on the sources of the raw materials, and commercially available products known to those skilled in the art may be used.

[0027] The present invention draws the niobium-titanium ingot to obtain the wire material.

[0028] In the present invention, the mass of titanium in the niobium-titanium ingot is preferably 47.5-48.5%; the mass of niobium in the niobium-titanium ingot is preferably 51.5-52.5%. As an embodiment, the mass of titanium in the niobium-titanium ingot can be 48%; the mass of niobium in the niobium-titanium ingot can be 52%.

[0029] In the present invention, the method for preparing the niobium-titanium ingot preferably comprises:

[0030] The niobium bars / rods and the titanium bars / rods are bundled into bundles, smelted in an electric arc furnace and cast in turn to obtain niobium-titanium ingots.

[0031] The present invention has no special limitation on the sizes of the niobium bars / rods and the titanium bars / rods, which can be adjusted according to actual needs.

[0032] As an implementation mode, the length, width and thickness of the niobium bar and the titanium bar may be 700×10×8 mm; the diameter of the niobium rod and the titanium rod may be 8-10 mm; the length of the niobium rod and the titanium rod may be 700 mm.

[0033] In the present invention, the purity of the niobium bars / rods and titanium bars / rods is preferably 4N. The present invention uses high-purity niobium bars / rods and titanium bars / rods to significantly improve the conditions of pores, broken wires, bamboo knots, multiple edge burrs and unclear boundaries in niobium-titanium superconducting wires.

[0034] The present invention has no special limitation on the preparation method of the niobium bars / rods and the titanium bars / rods, and operations familiar to those skilled in the art may be adopted.

[0035] The present invention has no special limitation on the ratio of the niobium bars / rods to the titanium bars / rods, as long as the composition of the niobium-titanium ingot meets the requirements.

[0036] In the present invention, the titanium strips / rods are preferably used as the core and the niobium strips / rods are preferably used as the wrapping when the bundles are bundled. The present invention uses titanium as the core material and niobium as the outer layer material. Niobium has a high melting point and a high arc starting temperature during smelting, which is more conducive to smelting.

[0037] The present invention has no special limitation on the specific operation of bundling, and operations well known to those skilled in the art may be adopted.

[0038] In the present invention, the number of times of the electric arc furnace smelting is preferably more than one. As an embodiment, the number of times of the electric arc furnace solution is preferably two. The present invention adopts electric arc furnace smelting to homogenize the alloy composition and evaporate and remove the impurity elements; adopting more than one electric arc furnace smelting can make the composition of the niobium-titanium ingot relatively uniform and eliminate pores.

[0039] As an embodiment, the temperature of the electric arc furnace smelting may be 2800°C.

[0040] The present invention has no special limitation on the casting operation, and operations well known to those skilled in the art may be adopted.

[0041] The present invention has no special limitation on the drawing operation, as long as the diameter of the wire material meets the requirements.

[0042] After the drawing is completed, the present invention preferably straightens, polishes, cuts and grinds the product obtained by the drawing in sequence to obtain the wire material.

[0043] The present invention has no special limitation on the straightening and polishing operations, and burrs and defects can be removed by using operations well known to those skilled in the art.

[0044] The present invention has no special limitation on the cutting operation, as long as the wire is cut into a wire with a length of 700 mm.

[0045] The present invention has no special limitation on the grinding operation, as long as the surface of the wire material is made smooth and flat.

[0046] In the present invention, the diameter of the wire is preferably 1.5 to 2.5 mm. As an embodiment, the diameter of the wire may be 2 mm. The present invention limits the diameter of the wire to the above range to facilitate subsequent processing.

[0047] As an embodiment, the length of the wire can be 700 mm. The present invention limits the length of the wire to 700 mm, which is beneficial to subsequent processing.

[0048] After obtaining the wire material, the present invention bundles the wire material to obtain bundled wire material.

[0049] In the present invention, niobium wire is preferably used to bind the two ends of the wires when the wires are bundled. The present invention has no special limitation on the size of the niobium wire, as long as the wires are bundled. The use of niobium wire in the present invention can prevent the bundled wires from falling apart.

[0050] The present invention has no special limitation on the number of wires in the bundle, and the number can be adjusted according to actual needs.

[0051] After obtaining the bundled wires, the present invention wraps the bundled wires with copper to obtain copper-wrapped wires. Niobium-titanium materials are difficult to draw into very thin wires, and the present invention uses copper wrapping to obtain thinner wires.

[0052] In the present invention, the copper wrapping is preferably performed by immersing the bundled wires in a copper melt or casting the copper melt on the bundled wires. The present invention has no particular limitation on the operation of immersing the bundled wires in a copper melt or casting the copper melt on the bundled wires, and the operation well known to those skilled in the art can be adopted.

[0053] In the present invention, the purity of the copper melt is preferably 5N. The present invention uses high-purity copper to significantly improve the conditions of pores, broken wires, bamboo knots, many edge burrs and unclear boundaries in niobium-titanium superconducting wires; and because high-purity copper is used as the coating material, the carrying current density, heat dissipation and stability of the niobium-titanium superconducting wires are qualitatively improved.

[0054] After the copper coating is completed, the present invention preferably cuts, turns and polishes the copper coated product in sequence to obtain the copper coated wire.

[0055] The present invention has no special limitation on the cutting operation, as long as the niobium wires used in bundling are cut off.

[0056] The present invention has no special limitation on the turning and polishing operations, as long as the surface is smooth.

[0057] In the present invention, the diameter of the copper-wrapped wire is preferably greater than the diameter of the bundled wire by 10 mm or more.

[0058] After obtaining the copper-wrapped wire, the present invention repeats the aforementioned drawing, bundling and copper-wrapping operations until the diameter of the niobium-titanium superconducting wire reaches 2-5 μm, thereby obtaining the niobium-titanium superconducting wire.

[0059] In the present invention, niobium-titanium wires or copper wires are preferably used for bundling. In the present invention, when the operations of drawing, bundling and copper wrapping are repeated, the use of niobium-titanium wires for bundling can ensure the stability of the composition of the niobium-titanium superconducting wires.

[0060] The present invention has no special limitation on the source of the copper wire, and the well-known high-purity copper wire in the present invention can be used.

[0061] The present invention uses copper as the wrapping material of the wire, which is conducive to heat dissipation. During repeated drawing, copper can reduce stress and avoid breakage during drawing. The repeated drawing process can reduce the diameter of the niobium-titanium wire to the micron level, ensuring the continuity, uniformity and stability of the niobium-titanium large bundle wire in the niobium-titanium superconducting wire, ensuring that no interruption or blocking phenomenon occurs when superconducting electricity is turned on under low temperature conditions, thereby ensuring the continuity and stability of the superconducting performance.

[0062] Compared with the traditional process, the present invention has the advantages of thin conductive wire diameter, large current, low cost, high production efficiency and simple process, and is suitable for the production of large-flux and large-scale superconducting wires. The present invention uses high-purity copper as the wrapping material, so that the diameter of the superconducting niobium-titanium wire can reach 2 to 5 μm, and the theoretical total length can reach 700 kilometers.

[0063] The present invention also provides a niobium-titanium superconducting wire prepared by the preparation method described in the above technical solution.

[0064] In the present invention, the diameter of the niobium-titanium superconducting wire is preferably 2-5 μm.

[0065] The present invention also provides the application of the niobium-titanium superconducting wire material described in the above technical solution in electric cables.

[0066] The present invention has no special limitation on the application operation of the niobium-titanium superconducting wire in the cable, and the application operation well known to those skilled in the art can be adopted.

[0067] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0068] Example 1

[0069] The preparation method of niobium-titanium superconducting wire is as follows:

[0070] (1) Cutting 4N purity niobium metal plates and 4N purity titanium metal plates into rods respectively, then bundling them into bundles, then performing electric arc furnace smelting twice at 2800° C., and then casting to obtain niobium-titanium ingots; wherein the diameter of the niobium rod and the titanium rod are both 8 mm and the length is 700 mm; when bundling into bundles, the titanium rod is the core and the niobium rod is the wrapping; the mass of titanium in the niobium-titanium ingot is 47.5%, and the mass of niobium is 52.5%;

[0071] (2) drawing the niobium-titanium ingot obtained in step (1), straightening and polishing the ingot in turn, and then cutting the ingot into 100 wires with a length of 700 mm, and grinding the wires to obtain wires with a diameter of 2 mm;

[0072] (3) bundling the 100 wires obtained in step (2), and tying both ends of the wires with niobium wire to obtain a bundle of wires;

[0073] (4) placing the bundled wire obtained in step (3) into a mold and pouring molten copper with a purity of 5N to coat the wire with copper, then cutting off the niobium wires bundled at both ends, and then sequentially turning and polishing the wire to obtain copper-coated wire; wherein the diameter of the copper-coated wire is 11 mm larger than the diameter of the bundled wire;

[0074] (5) Repeat steps (2) to (4) 5 times until the diameter of the niobium-titanium superconducting wire is 2 μm, and a niobium-titanium superconducting wire with a length of 15,000 meters is obtained.

[0075] The resistance of the niobium-titanium superconducting wire prepared in Example 1 approaches 0 at an ultra-low temperature of 4K (-269°C), indicating that the niobium-titanium superconducting wire prepared in Example 1 is a superconducting material.

[0076] The niobium-titanium superconducting wire prepared in Example 1 was professionally tested in the Low Temperature Superconducting Laboratory of Peking University. The high and low temperature resistivity test showed that the conduction result was intact, indicating that the niobium-titanium superconducting wire had no blocking phenomenon.

[0077] Application Example 1

[0078] The niobium-titanium superconducting wires prepared in Example 1 are bundled and wound with insulating varnish to form a cable.

[0079] It can be seen from the above embodiments that the diameter of the niobium-titanium superconducting wire provided by the present invention can be reduced to 2 μm.

[0080] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a niobium-titanium superconducting wire, comprising the following steps: (1) drawing the niobium-titanium ingot to obtain a wire; (2) bundling the wires obtained in step (1) to obtain bundled wires; (3) copper-coating the bundled wire obtained in step (2) to obtain copper-coated wire; (4) Repeat steps (1) to (3) until the diameter of the niobium-titanium superconducting wire reaches 2 to 5 μm, thereby obtaining the niobium-titanium superconducting wire.

2. The preparation method according to claim 1, characterized in that: The method for preparing the niobium-titanium ingot in step (1) comprises: The niobium bars / rods and the titanium bars / rods are bundled into bundles, smelted in an electric arc furnace and cast in turn to obtain niobium-titanium ingots.

3. The preparation method according to claim 2, characterized in that: When the bundles are bundled, the titanium bars / rods are used as cores and the niobium bars / rods are used as wrappers.

4. The preparation method according to claim 1, characterized in that: In the step (1), the mass of titanium in the niobium-titanium ingot is 47.5-48.5%, and the mass of niobium in the niobium-titanium ingot is 51.5-52.5%.

5. The preparation method according to claim 1, characterized in that: The diameter of the wire in step (1) is 1.5 to 2.5 mm.

6. The preparation method according to claim 5, characterized in that: The diameter of the wire is 2 mm.

7. The preparation method according to claim 1, characterized in that: In the step (3), the diameter of the copper-wrapped wire is at least 10 mm larger than the diameter of the bundled wire.

8. The niobium-titanium superconducting wire prepared by the preparation method according to any one of claims 1 to 7.

9. The niobium-titanium superconducting wire according to claim 8, characterized in that: The diameter of the niobium-titanium superconducting wire is 2-5 μm.

10. Use of the niobium-titanium superconducting wire according to claim 8 or 9 in electric cables.