The method of obtaining multi-fiber preform for manufacturing a superconducting wire based connections nb3sn (options)

 

The invention relates to the production of superconducting materials and can be used in the electrical industry and other branches of science and technology in the manufacture of superconducting magnetic systems for various purposes. The method of obtaining multi-fiber preform for manufacturing a superconducting wire based connections Nb3Sn includes the formation of a multi-fiber primary preform by placing in the case of the alloy of Cu-Sn Nb-containing rods, which deform and form a multi-fiber blank by placing rods obtained from the multi-fiber primary preform, in the case of copper or an alloy of Cu-Sn, while the formation of the multi-fiber primary preform Nb-containing rods are divided among themselves by placing between rods of alloy Cu-Sn, and the wall thickness of the cover multi-fiber primary preform is chosen in the range from 0.5 to 0.8 of the minimum distance between the nearest Nb-containing rods. In another embodiment, receiving the multi-fiber preform during formation of the multi-fiber primary preform Nb-containing rods are combined into blocks by placing between rods of alloy Cu-Sn, and the wall thickness of the case the primary rods, not belonging to the same block. The technical result of the proposed method consists in obtaining a conductor with a uniform arrangement of fibres in the cross section of the conductor and the increase of critical current density superconducting conductor in a field of 12 T at 15-30%. 2 C. p. F.-ly, 3 ill.

The invention relates to the production of superconducting materials and can be used in the electrical industry and other branches of science and technology in the manufacture of superconducting magnetic systems for various purposes.

A known method of manufacturing a multi-fiber preform to obtain a superconducting wire based connections Nb3Sn, whereby to form a multi-fiber blank by placing in the case of the alloy of Cu-Sn Nb-containing steel wire rods, deformed multi-fiber preparation, and, if necessary, obtain a large number of fibers, the formation stage multi-fiber preform and its deformation can be repeated in the case of rods, obtained from a previous multi-fiber preform [1].

When using this method, a uniform arrangement of fibres can be obtained only when tnostudy the e can substantially exceed 1,500 because of the significant technical difficulties in the formation of the workpiece. However, for conductors with high critical current density, which is provided by the fiber diameter in the finished wire about 2-3 μm, the number of fibers must substantially exceed this amount. Thus, the wire diameter of 0.7-0.8 mm contains, as a rule, 7-12 thousand fibers.

The closest technical solution adopted as a prototype, is a method for multi-fiber preform for the manufacture of a superconductor with a large number of Nb3Sn fibers, according to which first form the primary multi-fiber blank by placing in the case of the alloy of Cu-Sn Nb-containing rods, which deform to a rod of the desired size, and the rod cut-to-length line segments. From the bars of the primary preform to form a multi-fiber blank by placing these rods in the case of copper or an alloy of cu-Sn [2]. Multi-fiber hereinafter called the second workpiece obtained from rods multi-fiber primary preform.

The disadvantage of this method is the low value of the critical current density of the obtained superconducting wire due to the irregular arrangement of niobi deformed rod multi-fiber primary preform, located in the multi-fiber harvesting, surrounded fewer alloy of Cu-Sn, which is the source diffusion of the tin into the niobium for obtaining compounds of Nb3Sn than the fiber periphery of the strand.

The uneven distribution of the fibers in the finished wire, made from billet obtained according to the prototype, due to the fact that at the stage of formation of the multi-fiber preform the distance between the nearest Nb-containing rods belonging to neighboring strands, equal to twice the wall thickness of the cover multi-fiber primary preform after its deformation, and Nb-containing rods belonging to the same strand, in direct contact with each other.

The technical objective of the proposed method is to obtain uniform distribution of fibers in the cross section of the wire and increase the critical current density of the superconducting wire.

The specified technical task is achieved by the fact that in the proposed method of obtaining multi-fiber preform for manufacturing a superconducting wire based connections Nb3Sn, according to which form the primary multi-fiber blank by placing in the case of the alloy of Cu-Sn Nb-sedarah bars in the case of copper or an alloy of Cu-Sn, during the formation of the multi-fiber primary preform Nb-containing rods are divided among themselves by placing between rods of alloy Cu-Sn, and the wall thickness of the cover multi-fiber primary preform is chosen equal to 0.5 to 0.8 of the minimum distance between adjacent Nb-containing rods.

In another embodiment of the invention mentioned technical problem is achieved by the fact that in the proposed method of obtaining multi-fiber preform for manufacturing a superconducting wire based connections Nb3Sn, according to which form the primary multi-fiber blank by placing in the case of the alloy of Cu-Sn Nb-containing rods and deform it, and then of its bars form a multi-fiber blank by placing these rods in the case of copper or an alloy of Cu-Sn, while the formation of the multi-fiber primary preform Nb-containing rods are divided into equal number of bars blocks by placing between blocks rods of alloy Cu-Sn, and the wall thickness of the cover multi-fiber primary preform is chosen equal to 0.5 to 0.8 of the minimum distance between adjacent Nb-containing rods, not belonging to the same block.

In the present invention, when formed multi-fiber primary preform; 4 - case multi-fiber preform, the minimum distance between adjacent Nb-containing rods belonging to the same strand, is determined by the size placed between the rod of the alloy Cu-Sn, and the minimum distance between the nearest Nb-containing rods belonging to neighboring strands, is determined by twice the wall thickness of the cover multi-fiber primary preform. Thus, if the formation of the multi-fiber primary preform wall thickness of its case is chosen equal to half the lateral dimension of the rods of alloy Cu-Sn, at the stage of formation of the multi-fiber preform distance between any two adjacent Nb-containing rods are equal. Thus, between the Nb-containing rods of rods of alloy Cu-Sn in the primary multi-fiber procurement allows to obtain a uniform placement of the fibers in the finished wire.

When the deformation of the multi-fiber primary preform to the rod and the multi-fiber raw material to the finished wire peripheral rods multi-fiber primary preform, usually deformed unevenly, which leads to a distortion of their geometry in cross-section and appearance in the finished wire fiber pairs belonging acadesine loss in the wire. In case of high requirements to the wire on the hysteresis losses, the thickness of the cover of the first multi-fiber preform increase by 50-60%, which provides a guaranteed distance between fibers of adjacent strands and does not lead to a sharp increase in hysteresis loss. Accordingly, the wall thickness of the cover multi-fiber primary preform is chosen in the range of 0.5-0.8 minimum distance between adjacent Nb-containing rods.

Examples of specific performance.

Example 1.

Multi-fiber blank for manufacturing a superconducting wire containing 7641 fiber obtained by the method, including the formation of multi-fiber primary preform, its deformation and the formation of multi-fiber preform.

For the manufacture of multi-fiber primary preform 27 Nb-containing rods are placed in a case made of an alloy of Cu-Sn and in between the post 46 and rods of alloy of Cu-Sn. All rods have a hexagonal shape with a size of “turnkey” 8,65 mm. Outer diameter of the case is 94.0 mm, wall thickness of 4.5 mm

The scheme of Nb-containing rods in the primary multi-fiber to the workpiece shown in Fig.2, where 1 - Nb-containing rods, 2 - bars and rods, of alloy Cu-Sn, 3 - case primary hr/8856.gif">95 mm rod22 mm rod Received deformed with intermediate anneals to hex size “turnkey”, 3,1 mm Obtained hexagons cut to length and formed multi-fiber blank by placing the obtained hexagonal rods in the amount of 285 PCs in a copper case.

Obtained multi-fiber workpiece is deformed by squeezing on the rod22 mm lugs with intermediate anneals up to a diameter of 0.74 mm

On this wire, in a field of 12 Tesla was obtained critical current density 650 A/mm2that is 15% higher than the prototype.

Example 2.

Multi-fiber blank for manufacturing a superconducting wire containing 7596 fibers obtained by the method, including the formation of multi-fiber primary preform, its deformation and the formation of multi-fiber preform. The formation of the multi-fiber primary preform carried out by placing in the case of the alloy of Cu-Sn 36 blocks, each of which consisted of two Nb-containing rods of hexagonal shape with a size of “turnkey”, equal to 5.5 mm Blocks separated by placing between them hex rods, the diameter of the case was 93.5 mm, the wall thickness of 3.25 mm arrangement of blocks in the first multi-fiber to the workpiece shown in Fig.3 where, 1 - Nb-containing rods, 2 - bars and rods, of alloy Cu-Sn, 3 - case of the multi-fiber primary preform.

The resulting billet was caught in the press with force 1600 ie from the container95 mm rod22 mm rod Received deformed with intermediate anneals to hex size “turnkey”, equal to 3.6 mm, the resulting hexagons cut to length and formed multi-fiber preparation by their placement (211 units) in a copper case with a diameter of 95 mm

After deformation of the multi-fiber preform by extrusion and subsequent drawing with intermediate anneals to the diameter of 0.72mm shows the fiber diameter in the Explorer was 2.7 μm. On this wire in field 12 T was obtained critical current density 770 A/mm2that 200 a/mm2exceeds a critical current density of the prototype.

The thus obtained new technical result, which consists in receiving a wire with a uniform arrangement of fibres in the cross section and increase the critical current density of the superconducting wire in the editorship of S. Ferner and B. Schwartz, translation from English. M.: metallurgy, 1987, S. 282-283.

2. Patent of Russia №2050605 from 13.03.96, prototype.

Claims

1. The method of obtaining multi-fiber preform for manufacturing a superconducting wire based connections Nb3Sn, according to which form the primary multi-fiber blank by placing in the case of the alloy of Cu-Sn Nb-containing rods, which deform and form a multi-fiber blank by placing rods obtained from the multi-fiber primary preform, in the case of copper or an alloy of Cu-Sn, characterized in that when forming the multi-fiber primary preform Nb-containing rods are divided among themselves by placing between rods of alloy Cu-Sn, and the wall thickness of the cover multi-fiber primary preform is chosen in the range from 0.5 to 0.8 of the minimum distance between the nearest Nb-containing rods.

2. The method of obtaining multi-fiber preform for manufacturing a superconducting wire based connections Nb3Sn, according to which form the primary multi-fiber blank by placing in the case of the alloy of Cu-Sn Nb-containing rods, which deform and form a multi-fiber Sn, characterized in that when forming the multi-fiber primary preform Nb-containing rods are combined into blocks by placing between rods of alloy Cu-Sn, and the wall thickness of the cover multi-fiber primary preform is chosen in the range from 0.5 to 0.8 of the minimum distance between the nearest Nb-containing rods, not belonging to the same block.

 

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