A method for preparing Nb3Sn superconducting wire by internal tin method

Abstract

The present invention discloses a method for preparing an internal tin method Nb3Sn superconducting wire, comprising the following steps: using 3D printing technology to print a porous CuTi alloy ingot, inserting a Nb rod and sealing it; performing hot extrusion; drilling a hole at the center of a CuTi / Nb composite rod, inserting a SnCu alloy rod into the center hole, obtaining a superconducting subcomponent, drawing and then cutting it into a number of equal lengths, and evenly arranging them; loading the superconducting subcomponent assembly into a Ta tube, and then loading the Ta tube into an oxygen-free copper tube; drawing and twisting the final billet to obtain an internal tin method Nb3Sn superconducting wire; and performing heat treatment. The present application obtains a porous CuTi alloy ingot by combining 3D printing technology with the high-strength characteristics of CuTi alloy, thereby improving the deformation uniformity and distribution uniformity of the Nb core wire during wire processing, suppressing the overlap of the core wire, and achieving a reduction in the loss value of the superconducting wire.

Description

Technical Field

[0001] The present application relates to the technical field of superconducting wire preparation, and in particular to a method for preparing Nb3Sn superconducting wire by an internal tin process. Background Art

[0002] Internal tin method Nb3Sn superconducting wire is an important material for manufacturing large particle accelerators. At present, the critical current density of internal tin method Nb3Sn superconducting wire delivered in batches in various scientific projects in the world can reach 1100-1300A / mm under 12T and 4.2K conditions. 2 , the wire loss value is generally 500mJ·cm -3 It is necessary to study the preparation of Nb3Sn superconducting wires with lower loss values ​​by the internal tin method to meet the demand for low-loss Nb3Sn superconducting wires in many application scenarios.

[0003] In the prior art, Chinese patent CN115938678A discloses a method for manufacturing a niobium-tin precursor wire by an internal tin method. By adding a layer of oxygen-free copper foil between the barrier layer and the subcomponent of the Nb3Sn final billet, while reducing the thickness of the copper layer on the outside of the subcomponent and increasing the proportion of the Nb element, the risk of contact between the Nb core wire inside the subcomponent and the Ta barrier layer during the final billet stretching process is effectively reduced. In addition, the oxygen-free copper foil can improve the deformation of the Ta barrier layer on its outside and reduce the risk of rupture of the barrier layer during the stretching process.

[0004] The main factor affecting the loss of Nb3Sn superconducting wires by the internal tin method is that the original oxygen-free copper matrix has low strength during the wire processing, which leads to the overlap of Nb core wires in the wire during the processing; in addition, during the heat treatment stage of Nb3Sn superconducting wires by the internal tin method at a temperature below 600°C, the Cu element around the Nb core wire will gradually diffuse to the center of the subcomponent with a higher Sn content, resulting in the formation of holes between the Nb core wires and the Nb core wires. Finally, the wire undergoes a phase reaction with Nb3Sn, the core wire volume increases, and the Nb core wire overlaps, resulting in a higher loss value for the superconducting wire. However, the above-mentioned prior art does not take into account the overlap of Nb core wires, and the deformation uniformity and distribution uniformity of the Nb core wires during the wire processing are poor, resulting in a higher loss value for the superconducting wire. Summary of the invention

[0005] The present application provides a method for preparing Nb3Sn superconducting wire by internal tin method, which is used to solve the problems that the prior art does not consider the overlap of Nb core wires, the deformation uniformity and distribution uniformity of Nb core wires during wire processing are poor, and the loss value of superconducting wires is high.

[0006] On the one hand, the present application provides a method for preparing a Nb3Sn superconducting wire by an internal tin method, comprising the following steps:

[0007] Step 1: Use 3D printing technology to print CuTi alloy into a porous CuTi alloy ingot, insert Nb rods whose number and diameter match the number and diameter of holes of the porous CuTi alloy ingot into the porous CuTi alloy ingot and seal them to obtain a CuTi / Nb composite sheath.

[0008] Step 2: hot-extrude the CuTi / Nb composite sheath to obtain a CuTi / Nb composite rod.

[0009] Step three, drilling a hole at the center position of the CuTi / Nb composite rod, inserting a SnCu alloy rod into the center hole of the CuTi / Nb composite rod to obtain an internal tin method Nb3Sn superconducting subcomponent, drawing and cutting the internal tin method Nb3Sn superconducting subcomponent into a plurality of equal lengths, and evenly arranging them to obtain a superconducting subcomponent set.

[0010] Step 4: Load the superconducting subcomponent assembly into a Ta tube, and then load the Ta tube loaded with the superconducting subcomponent assembly into an oxygen-free copper tube to obtain a final billet.

[0011] Step five, drawing and twisting the final billet to obtain an internal tin method Nb3Sn superconducting wire.

[0012] Step six, heat treating the internal tin method Nb3Sn superconducting wire.

[0013] In a possible implementation, in step 1, the mass percentage of the Ti element in the porous CuTi alloy ingot is 1.5% to 2.0%.

[0014] In a possible implementation, in step 1, the number of the Nb rods is 140 to 200, and the diameter is 9 to 12 mm; the diameter of the porous CuTi alloy ingot is 280 to 300 mm.

[0015] In a possible implementation, in step 2, the extrusion temperature of the hot extrusion is 700 to 900° C., and the holding time is 60 to 90 minutes.

[0016] In a possible implementation, in step 2, the diameter of the CuTi / Nb composite rod is 52 to 75 mm.

[0017] In a possible implementation, in step three, the diameter of the center hole is 20 to 23 mm, and the diameter of the SnCu alloy rod is 1 mm smaller than the diameter of the center hole.

[0018] In a possible implementation, in step three, the opposite side dimensions of the formed hexagonal superconducting subcomponent after drawing are H5 to H15 mm.

[0019] In a possible implementation, in step 4, the outer diameter of the oxygen-free copper tube is 60 to 75 mm, and the inner diameter is 45 to 60 mm; the outer diameter of the Ta tube is 1 mm smaller than the inner diameter of the oxygen-free copper tube.

[0020] In a possible implementation, in step five, the diameter of the internal tin method Nb3Sn superconducting wire is 0.8 to 1.3 mm, and the twisting pitch is 15 to 40 mm.

[0021] In a possible implementation, in step six, the heat treatment adopts a standard internal tin method Nb3Sn heat treatment process.

[0022] The parameters of the standard internal tin method Nb3Sn heat treatment process are:

[0023] 210℃×50h+340℃×25h+450℃×25h+575℃×100h+650℃×100h, the heating rate during the heat treatment is 5℃ / h.

[0024] The method for preparing Nb3Sn superconducting wire by internal tin method in the present application has the following advantages:

[0025] By combining 3D printing technology and the high-strength characteristics of CuTi alloy, a porous CuTi alloy ingot was obtained, which achieved an improvement in matrix strength and an improvement in the uniformity of pore distribution. This in turn improved the deformation uniformity and distribution uniformity of the Nb core wire during wire processing, inhibited core wire overlap, and achieved a reduction in the loss value of the superconducting wire. 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 a Nb3Sn superconducting wire by an internal tin method provided in an embodiment of the present application;

[0028] Figure 2 A schematic cross-sectional view of a CuTi / Nb composite sheath provided in an embodiment of the present application;

[0029] Figure 3 This is a schematic cross-sectional view of the internal tin method Nb3Sn superconducting wire provided in an embodiment of the present application.

[0030] Description of reference numerals:

[0031] 1-Nb rod, 2-porous CuTi alloy ingot, 3-oxygen-free copper tube, 4-Ta tube, 5-superconducting subcomponent assembly. DETAILED DESCRIPTION

[0032] 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.

[0033] like Figures 1 to 3 As shown, the embodiment of the present application provides a method for preparing a Nb3Sn superconducting wire by an internal tin method, comprising the following steps:

[0034] Step 1: Use 3D printing technology to print CuTi alloy into a porous CuTi alloy ingot 2, insert Nb rods 1 whose number and diameter match the number and diameter of holes of the porous CuTi alloy ingot 2 into the porous CuTi alloy ingot 2 and seal them to obtain a CuTi / Nb composite sheath.

[0035] Step 2: hot-extrude the CuTi / Nb composite sheath to obtain a CuTi / Nb composite rod.

[0036] Step three, drilling a hole at the center position of the CuTi / Nb composite rod, inserting a SnCu alloy rod into the center hole of the CuTi / Nb composite rod to obtain an internal tin method Nb3Sn superconducting subcomponent, drawing and cutting the internal tin method Nb3Sn superconducting subcomponent into a plurality of equal lengths, and arranging them evenly to obtain a superconducting subcomponent set 5.

[0037] Step 4: Load the superconducting subcomponent assembly 5 into the Ta tube 4, and then load the Ta tube 4 loaded with the superconducting subcomponent assembly 5 into the oxygen-free copper tube 3 to obtain a final blank.

[0038] Step five, drawing and twisting the final billet to obtain an internal tin method Nb3Sn superconducting wire.

[0039] Step six, heat treating the internal tin method Nb3Sn superconducting wire.

[0040] Embodiment 1:

[0041] Exemplarily, in this embodiment, in step one, 3D printing technology is used to print the CuTi alloy into a porous CuTi alloy ingot 2 with 140 holes, the diameter of the porous CuTi alloy ingot 2 is 280 mm, and the mass proportion of the Ti element in the porous CuTi alloy ingot 2 is 1.5%. 140 Nb rods 1 with a diameter matching the hole diameter of the porous CuTi alloy ingot 2 are inserted into the porous CuTi alloy ingot 2 to form a CuTi / Nb composite ingot, the diameter of the Nb rod 1 is 9 mm, and CuTi covers are added to both ends of the CuTi / Nb composite ingot and electron beam sealing is performed to obtain a CuTi / Nb composite sheath.

[0042] In step 2, the extrusion temperature of hot extrusion is 700° C., the holding time is 60 min, and the diameter of the obtained CuTi / Nb composite rod is 52 mm.

[0043] In step three, a hole is drilled at the center position of the CuTi / Nb composite rod, and the SnCu alloy rod is inserted into the center hole of the CuTi / Nb composite rod to obtain an internal tin method Nb3Sn superconducting subcomponent. The diameter of the center hole is 20mm, and the diameter of the SnCu alloy rod is 1mm smaller than the diameter of the center hole. The internal tin method Nb3Sn superconducting subcomponent is drawn and cut into several equal lengths. The opposite side size of the drawn formed hexagonal superconducting subcomponent is H5mm.

[0044] In step 4, the superconducting subcomponent assembly 5 is loaded into the Ta tube 4, and then the Ta tube 4 loaded with the superconducting subcomponent assembly 5 is loaded into the oxygen-free copper tube 3 to obtain the final billet. The outer diameter of the oxygen-free copper tube 3 is 60 mm and the inner diameter is 45 mm. The outer diameter of the Ta tube 4 is 1 mm smaller than the inner diameter of the oxygen-free copper tube 3.

[0045] In step five, the final billet is drawn and twisted to obtain an internal tin method Nb3Sn superconducting wire. The internal tin method Nb3Sn superconducting wire has a diameter of 0.8 mm and a twisting pitch of 15 mm.

[0046] In step 6, the internal tin method Nb3Sn superconducting wire is heat treated by a standard internal tin method Nb3Sn heat treatment process, and the parameters of the standard internal tin method Nb3Sn heat treatment process are:

[0047] 210℃×50h+340℃×25h+450℃×25h+575℃×100h+650℃×100h, the heating rate during the heat treatment is 5℃ / h. The critical current value of the internal tin method Nb3Sn superconducting wire after the heat treatment in Example 1 is measured to obtain its loss value.

[0048] The loss value of the Nb3Sn superconducting wire obtained by the internal tin method in Example 1 was compared with the loss value of the superconducting wire of the same specification prepared by the conventional internal tin method. The loss value of the Nb3Sn superconducting wire obtained by the internal tin method in Example 1 was 350.2 mJ·cm -3 The loss value of superconducting wire with the same specifications prepared by conventional internal tin method is 561.3mJ·cm -3 In this embodiment 1, a 11000 m long Nb3Sn superconducting wire using the internal tin method is successfully prepared, and its loss value is significantly lower than that of a superconducting wire of the same specification prepared using the conventional internal tin method.

[0049] Embodiment 2:

[0050] Exemplarily, in this embodiment, in step one, 3D printing technology is used to print the CuTi alloy into a porous CuTi alloy ingot 2 with 160 holes, the diameter of the porous CuTi alloy ingot 2 is 290 mm, and the mass proportion of the Ti element in the porous CuTi alloy ingot 2 is 1.8%. 160 Nb rods 1 with a diameter matching the hole diameter of the porous CuTi alloy ingot 2 are inserted into the porous CuTi alloy ingot 2 to form a CuTi / Nb composite ingot, the diameter of the Nb rod 1 is 10 mm, and CuTi covers are added to both ends of the CuTi / Nb composite ingot and electron beam sealing is performed to obtain a CuTi / Nb composite sheath.

[0051] In step 2, the extrusion temperature of hot extrusion is 800° C., the holding time is 70 min, and the diameter of the obtained CuTi / Nb composite rod is 65 mm.

[0052] In step three, a hole is drilled at the center of the CuTi / Nb composite rod, and the SnCu alloy rod is inserted into the center hole of the CuTi / Nb composite rod to obtain an internal tin method Nb3Sn superconducting subcomponent. The diameter of the center hole is 22 mm, and the diameter of the SnCu alloy rod is 1 mm smaller than the diameter of the center hole. The internal tin method Nb3Sn superconducting subcomponent is drawn and cut into several equal lengths. The opposite side size of the drawn formed hexagonal superconducting subcomponent is H10 mm.

[0053] In step 4, the superconducting subcomponent assembly 5 is loaded into the Ta tube 4, and then the Ta tube 4 loaded with the superconducting subcomponent assembly 5 is loaded into the oxygen-free copper tube 3 to obtain the final billet. The outer diameter of the oxygen-free copper tube 3 is 65 mm and the inner diameter is 50 mm. The outer diameter of the Ta tube 4 is 1 mm smaller than the inner diameter of the oxygen-free copper tube 3.

[0054] In step five, the final billet is drawn and twisted to obtain an internal tin method Nb3Sn superconducting wire. The diameter of the internal tin method Nb3Sn superconducting wire is 0.988 mm and the twisting pitch is 30 mm.

[0055] In step 6, the internal tin method Nb3Sn superconducting wire is heat treated by a standard internal tin method Nb3Sn heat treatment process, and the parameters of the standard internal tin method Nb3Sn heat treatment process are:

[0056] 210℃×50h+340℃×25h+450℃×25h+575℃×100h+650℃×100h, the heating rate during the heat treatment is 5℃ / h. The critical current value of the internal tin method Nb3Sn superconducting wire after the heat treatment in Example 2 is measured to obtain its loss value.

[0057] The loss value of the Nb3Sn superconducting wire obtained by the internal tin method in Example 2 was compared with the loss value of the superconducting wire of the same specification prepared by the conventional internal tin method. The loss value of the Nb3Sn superconducting wire obtained by the internal tin method in Example 2 was 310.7 mJ·cm -3 The loss value of superconducting wire with the same specifications prepared by conventional internal tin method is 520.9mJ·cm -3 In this Example 2, a 9000 m long Nb3Sn superconducting wire using the internal tin method was successfully prepared, and its loss value was significantly lower than that of a superconducting wire of the same specification prepared using the conventional internal tin method.

[0058] Embodiment 3:

[0059] Exemplarily, in this embodiment, in step one, the CuTi alloy is printed into a porous CuTi alloy ingot 2 with 200 holes by 3D printing technology, the diameter of the porous CuTi alloy ingot 2 is 300 mm, and the mass proportion of the Ti element in the porous CuTi alloy ingot 2 is 2.0%. 200 Nb rods 1 with a diameter matching the hole diameter of the porous CuTi alloy ingot 2 are inserted into the porous CuTi alloy ingot 2 to form a CuTi / Nb composite ingot, the diameter of the Nb rod 1 is 12 mm, and CuTi covers are added to both ends of the CuTi / Nb composite ingot and electron beam sealing is performed to obtain a CuTi / Nb composite sheath.

[0060] In step 2, the extrusion temperature of hot extrusion is 900° C., the holding time is 90 min, and the diameter of the obtained CuTi / Nb composite rod is 75 mm.

[0061] In step three, a hole is drilled at the center position of the CuTi / Nb composite rod, and the SnCu alloy rod is inserted into the center hole of the CuTi / Nb composite rod to obtain an internal tin method Nb3Sn superconducting subcomponent. The diameter of the center hole is 23mm, and the diameter of the SnCu alloy rod is 1mm smaller than the diameter of the center hole. The internal tin method Nb3Sn superconducting subcomponent is drawn and cut into several equal lengths. The opposite side size of the drawn formed hexagonal superconducting subcomponent is H15mm.

[0062] In step 4, the superconducting subcomponent assembly 5 is loaded into the Ta tube 4, and then the Ta tube 4 loaded with the superconducting subcomponent assembly 5 is loaded into the oxygen-free copper tube 3 to obtain the final billet. The outer diameter of the oxygen-free copper tube 3 is 75 mm and the inner diameter is 60 mm. The outer diameter of the Ta tube 4 is 1 mm smaller than the inner diameter of the oxygen-free copper tube 3.

[0063] In step five, the final billet is drawn and twisted to obtain an internal tin method Nb3Sn superconducting wire. The internal tin method Nb3Sn superconducting wire has a diameter of 1.3 mm and a twisting pitch of 40 mm.

[0064] In step 6, the internal tin method Nb3Sn superconducting wire is heat treated by a standard internal tin method Nb3Sn heat treatment process, and the parameters of the standard internal tin method Nb3Sn heat treatment process are:

[0065] 210℃×50h+340℃×25h+450℃×25h+575℃×100h+650℃×100h, the heating rate during the heat treatment is 5℃ / h. The critical current value of the internal tin method Nb3Sn superconducting wire after the heat treatment in Example 3 is measured to obtain its loss value.

[0066] The loss value of the Nb3Sn superconducting wire obtained by the internal tin method in Example 3 was compared with the loss value of the superconducting wire of the same specification prepared by the conventional internal tin method. The loss value of the Nb3Sn superconducting wire obtained by the internal tin method in Example 3 was 290.8 mJ·cm -3 The loss value of superconducting wire with the same specifications prepared by conventional internal tin method is 430.5mJ·cm -3 In this embodiment 3, a 6000 m long Nb3Sn superconducting wire using the internal tin method is successfully prepared, and its loss value is significantly lower than that of a superconducting wire of the same specification prepared using the conventional internal tin method.

[0067] The embodiment of the present application obtains a porous CuTi alloy ingot 2 by combining 3D printing technology and the high-strength characteristics of CuTi alloy, thereby achieving an improvement in matrix strength and an improvement in the uniformity of pore distribution, thereby improving the deformation uniformity and distribution uniformity of the Nb core wire during wire processing, inhibiting core wire overlap, and achieving a reduction in the loss value of the superconducting wire.

[0068] 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.

[0069] 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 Nb3Sn superconducting wire by internal tin method, characterized in that: The following steps are involved: Step 1: Use 3D printing technology to print CuTi alloy into a porous CuTi alloy ingot, insert Nb rods whose number and diameter match the number and diameter of holes of the porous CuTi alloy ingot into the porous CuTi alloy ingot and perform sealing welding to obtain a CuTi / Nb composite sheath; Step 2, hot extruding the CuTi / Nb composite sheath to obtain a CuTi / Nb composite rod; Step 3, drilling a hole at the center position of the CuTi / Nb composite rod, inserting a SnCu alloy rod into the center hole of the CuTi / Nb composite rod, obtaining an inner tin method Nb3Sn superconducting subcomponent, drawing and cutting the inner tin method Nb3Sn superconducting subcomponent into a plurality of equal lengths, and evenly arranging them to obtain a superconducting subcomponent set; Step 4, loading the superconducting subcomponent assembly into a Ta tube, and then loading the Ta tube loaded with the superconducting subcomponent assembly into an oxygen-free copper tube to obtain a final billet; Step 5, drawing and twisting the final billet to obtain an internal tin method Nb3Sn superconducting wire; Step six, heat treating the internal tin method Nb3Sn superconducting wire.

2. The method for preparing a Nb3Sn superconducting wire by an internal tin method according to claim 1, characterized in that: In step 1, the mass proportion of Ti element in the porous CuTi alloy ingot is 1.5% to 2.0%.

3. The method for preparing a Nb3Sn superconducting wire by an internal tin method according to claim 1, characterized in that: In step 1, the number of the Nb rods is 140 to 200, and the diameter is 9 to 12 mm; the diameter of the porous CuTi alloy ingot is 280 to 300 mm.

4. The method for preparing a Nb3Sn superconducting wire by an internal tin method according to claim 1, characterized in that: In step 2, the extrusion temperature of the hot extrusion is 700 to 900° C., and the insulation time is 60 to 90 minutes.

5. The method for preparing a Nb3Sn superconducting wire by an internal tin method according to claim 1, characterized in that: In step 2, the diameter of the CuTi / Nb composite rod is 52 to 75 mm.

6. The method for preparing a Nb3Sn superconducting wire by an internal tin method according to claim 1, characterized in that: In step three, the diameter of the center hole is 20 to 23 mm, and the diameter of the SnCu alloy rod is 1 mm smaller than the diameter of the center hole.

7. The method for preparing a Nb3Sn superconducting wire by an internal tin method according to claim 1, characterized in that: In step 3, the opposite side dimensions of the formed hexagonal superconducting subcomponent after drawing are H5 to H15 mm.

8. The method for preparing a Nb3Sn superconducting wire by an internal tin method according to claim 1, characterized in that: In step 4, the outer diameter of the oxygen-free copper tube is 60 to 75 mm, and the inner diameter is 45 to 60 mm; the outer diameter of the Ta tube is 1 mm smaller than the inner diameter of the oxygen-free copper tube.

9. The method for preparing a Nb3Sn superconducting wire by an internal tin method according to claim 1, characterized in that: In step 5, the diameter of the internal tin method Nb3Sn superconducting wire is 0.8 to 1.3 mm, and the twisting pitch is 15 to 40 mm.

10. The method for preparing a Nb3Sn superconducting wire by an internal tin method according to claim 1, characterized in that: In step six, the heat treatment adopts a standard internal tin method Nb3Sn heat treatment process; The parameters of the standard internal tin method Nb3Sn heat treatment process are: 210℃×50h+340℃×25h+450℃×25h+575℃×100h+650℃×100h, the heating rate during the heat treatment is 5℃ / h.

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