A method for preparing an artificial pinning center niobium-tritantalum sub-component

Abstract

The application belongs to the technical field of superconducting material processing, and discloses a preparation method of an artificial pinning center niobium-tin subelement. The method uses a Nb or Nb alloy foil plated with a Cu layer as an initial raw material. In the subsequent processing of the subelement and the Nb3Sn composite wire, the size of the Cu layer is continuously reduced, and finally reaches the nanometer level. After the final heat treatment, Sn diffuses into the Nb or Nb alloy to form an Nb3Sn phase, and the position of the Cu layer is converted into a non-superconducting bronze phase, which effectively serves as a pinning center of the Nb3Sn, and significantly improves the critical current density of the wire. Meanwhile, the process route of the application is simple, and solves the problems of difficult processing and unsuitable batch production of the artificial pinning center niobium-tin subelement.

Description

Technical Field

[0001] This invention relates to the field of superconducting material processing technology, specifically to a method for preparing an artificially pinned niobium-tin subunit. Background Technology

[0002] Nb3Sn superconducting wires, with their superior performance and relatively low cost, have unique advantages in manufacturing 10T–20T magnets and are widely used in fields such as nuclear fusion, accelerators, and medical imaging. With the advancement of technology, higher performance requirements have been placed on Nb3Sn wires. Over the past two decades, the performance of traditional Nb3Sn wires has reached a bottleneck, necessitating new methods to further improve the critical current density of Nb3Sn.

[0003] Practical Nb3Sn wire is a typical non-ideal type-II superconductor. Introducing artificial pinning centers can increase pinning force density, thereby raising the critical current density. For artificial pinning centers to be effective, two conditions must be met. First, the coherence length of Nb3Sn at low temperatures must be on the nanometer scale, and the size of the artificial pinning centers must match this. Second, the artificial pinning centers must exist in the Nb3Sn as second-phase particles. These two points make the introduction of artificial pinning centers extremely difficult. Internal oxidation is currently a relatively reliable process. It uses dopants miscible with Nb to form an alloy with Nb, while simultaneously introducing oxygen into the composite wire as oxide powder. During heat treatment, oxygen diffuses into the Nb alloy matrix, forming nanometer-sized second-phase oxide particles with the dopants, serving as artificial pinning centers. This method is not only complex in its process but also requires the introduction of powder during processing, making mass production difficult. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing artificially pinned niobium tritin subunits, so as to solve the problem of complex process of introducing artificial pinning centers into Nb3Sn wires mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for preparing an artificially pinned central niobium-tin subunit includes the following steps:

[0007] Step 1: Pickle the long strip of Nb or Nb alloy foil, and then use electroplating to form a uniform Cu layer on the surface of the Nb or Nb alloy foil. Finally, wind it onto a copper rod and put it into a copper cladding.

[0008] Step 2: Degas the obtained copper cladding, assemble the upper and lower covers at both ends, and perform electron beam sealing to obtain CuNb cladding.

[0009] Step 3: After heating and holding the obtained CuNb cladding at a certain temperature, it is extruded to obtain CuNb composite rods;

[0010] Step 4: Drill holes along the length of the obtained CuNb composite rod and clean it. After cleaning, insert a Sn alloy rod to obtain a niobium tritin subunit billet.

[0011] Step 5: Perform multiple cold drawing operations on the obtained niobium tritin subunit billet to obtain artificially pinned niobium tritin subunits.

[0012] More preferably, in step 1, the Nb alloy of the Nb alloy foil is Nb-Ta, and the amount of Ta added is 0.5 at.% to 5 at.%.

[0013] More preferably, the thickness of the Nb or Nb alloy foil in step 1 is 0.1 mm to 0.3 mm.

[0014] More preferably, in step 1, when a uniform Cu layer is formed on the surface of Nb or Nb alloy foil, the thickness of Cu is 3 μm to 11 μm.

[0015] More preferably, the CuNb cladding size obtained in step 2 is φ92mm~225mm.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] This invention uses Nb or Nb alloy foil with an electroplated Cu layer as the initial raw material. During the subsequent processing of the sub-components and Nb3Sn composite wire, the size of the Cu layer continuously decreases, eventually reaching the nanometer scale. After final heat treatment, Sn diffuses into the Nb or Nb alloy to form the Nb3Sn phase, while the Cu layer transforms into a non-superconducting bronze phase, effectively serving as a pinning center for Nb3Sn and significantly increasing the critical current density of the wire. Simultaneously, the process route of this invention is simple, solving the problems of difficult processing and unsuitability for mass production of niobium-tin sub-components with artificially pinned centers using the internal oxidation method. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the preparation process of the present invention;

[0019] Figure 2 This is a cross-sectional view of the CuNb cladding of the present invention;

[0020] Figure 3 This is a cross-sectional view of the niobium tritin subunit billet of the present invention; Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1-3 The present invention provides a technical solution:

[0023] A method for preparing an artificially pinned central niobium-tin subunit includes the following steps:

[0024] Step 1: Pickle the long strip of Nb or Nb alloy foil, and then use electroplating to form a uniform Cu layer on the surface of the Nb or Nb alloy foil. Finally, wind it onto a copper rod and put it into a copper cladding.

[0025] Step 2: Degas the obtained copper cladding, assemble the upper and lower covers at both ends, and perform electron beam sealing to obtain CuNb cladding.

[0026] Step 3: After heating and holding the obtained CuNb cladding at a certain temperature, it is extruded to obtain CuNb composite rods;

[0027] Step 4: Drill holes along the length of the obtained CuNb composite rod and clean it. After cleaning, insert a Sn alloy rod to obtain a niobium tritin subunit billet.

[0028] Step 5: Perform multiple cold drawing operations on the obtained niobium tritin subunit billet to obtain artificially pinned niobium tritin subunits.

[0029] In this invention, the Nb alloy of the Nb alloy foil in step 1 is Nb-Ta, and the amount of Ta added is 0.5 at.% to 5 at.%.

[0030] In this invention, the thickness of the Nb or Nb alloy foil in step 1 is 0.1 mm to 0.3 mm.

[0031] In this invention, when a uniform Cu layer is formed on the surface of Nb or Nb alloy foil in step 1, the thickness of Cu is 3 μm to 11 μm.

[0032] In this invention, the CuNb cladding size obtained in step 2 is φ92mm~225mm.

[0033] Example 1

[0034] A long strip of Nb4at.%Ta alloy foil with a thickness of 0.1 mm was pickled, and a uniform Cu layer with a thickness of 3 μm was formed on the surface of the Nb4at.%Ta alloy foil by electroplating. The foil was then wound onto a φ40 mm copper rod, resulting in an outer diameter of 80 mm. Finally, it was placed into a φ92 mm / φ80.5 mm copper sheath.

[0035] The obtained copper cladding was degassed, and upper and lower covers were assembled at both ends and electron beam sealed to obtain a CuNb cladding with a size of φ92mm.

[0036] The obtained CuNb cladding was heated to 550℃ and held for 1 hour, and then extruded to obtain a CuNb composite rod with a diameter of 24.5 mm.

[0037] A φ9.5mm hole was drilled along the length of the obtained CuNb composite rod, and the rod was cleaned. After cleaning, a φ9mm Sn alloy rod was inserted to obtain a niobium tritin subunit billet.

[0038] The obtained niobium tritin subunit billet was subjected to multiple cold drawing passes to obtain artificially pinned niobium tritin subunits.

[0039] The niobium-tin wire prepared using this subcomponent achieved a critical current density of 3100 A / mm² under conditions of 4.2 K temperature and 12 T magnetic field. 2 This represents an improvement of approximately 14.8% compared to ordinary cables.

[0040] Example 2

[0041] A long strip of 0.3mm thick Nb foil was acid-washed, and a uniform 11µm thick Cu layer was formed on the surface of the Nb foil using electroplating. This was then wound onto a 97.3mm thick copper rod, resulting in an outer diameter of 194.6mm. Finally, it was placed into a 225mm / 195mm copper sheath.

[0042] The obtained copper cladding was degassed, and upper and lower covers were assembled at both ends and electron beam sealed to obtain a CuNb cladding with a size of φ225mm.

[0043] The obtained CuNb cladding was heated to 550℃ and held for 2 hours before being extruded to obtain a CuNb composite rod with a diameter of 80mm.

[0044] A φ31.0mm hole was drilled along the length of the obtained CuNb composite rod, and the rod was cleaned. After cleaning, a φ30.5mm Sn alloy rod was inserted to obtain a niobium tritin subunit billet.

[0045] The obtained niobium tritin subunit billet was subjected to multiple cold drawing passes to obtain artificially pinned niobium tritin subunits.

[0046] The niobium-tin wire prepared using this subcomponent achieved a critical current density of 3000 A / mm² under conditions of 4.2 K temperature and 12 T magnetic field. 2 This represents an improvement of approximately 11.1% compared to ordinary cables.

[0047] Example 3

[0048] A long strip of 0.2mm thick Nb foil is acid-washed, and a uniform 6µm thick Cu layer is formed on the surface of the Nb foil by electroplating. The foil is then wound onto a 90mm diameter copper rod, resulting in an outer diameter of 180mm. Finally, it is placed into a 138mm / 119mm copper sheath.

[0049] The obtained copper cladding was degassed, and upper and lower covers were assembled at both ends and electron beam sealed to obtain a CuNb cladding with a size of φ138mm.

[0050] The obtained CuNb cladding was heated to 550℃ and held for 2 hours, and then extruded to obtain a CuNb composite rod with a diameter of φ40mm.

[0051] A φ15.5mm hole was drilled along the length of the obtained CuNb composite rod, and the rod was cleaned. After cleaning, a φ15mm Sn alloy rod was inserted to obtain a niobium tritin subunit billet.

[0052] The obtained niobium tritin subunit billet was subjected to multiple cold drawing passes to obtain artificially pinned niobium tritin subunits.

[0053] The niobium-tin wire prepared using this subcomponent achieved a critical current density of 2930 A / mm² under conditions of 4.2 K temperature and 12 T magnetic field. 2 This represents an improvement of approximately 8.5% compared to ordinary cables.

[0054] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0055] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an artificially pinned central niobium-tin subunit, characterized in that, Includes the following steps: Step 1: Pickle the long strip of Nb or Nb alloy foil, and then electroplat it to form a uniform Cu layer on the surface of the Nb or Nb alloy foil. Then, wind it onto a copper rod and put it into a copper sleeve. The Nb alloy of the Nb alloy foil is Nb-Ta, and the amount of Ta added is 0.5 at.% to 5 at.%. When a uniform Cu layer is formed on the surface of the Nb or Nb alloy foil, the thickness of Cu is 3 μm to 11 μm, and the thickness of the Nb or Nb alloy foil is 0.1 mm to 0.3 mm. Step 2: Degas the obtained copper cladding, assemble the upper and lower covers at both ends, and perform electron beam sealing to obtain CuNb cladding. The size of the CuNb cladding is φ92mm~225mm. Step 3: After heating and holding the obtained CuNb cladding at a certain temperature, it is extruded to obtain CuNb composite rods; Step 4: Drill holes along the length of the obtained CuNb composite rod and clean it. After cleaning, insert a Sn alloy rod to obtain a niobium tritin subunit billet. Step 5: Perform multiple cold drawing operations on the obtained niobium tritin subunit billet to obtain artificially pinned niobium tritin subunits.

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