Fabrication of Bi-Based Superconductor

Recent achievements in the newly-developed Bi-2212/Ag round-shaped wire with tape-shaped multifilaments are summarized. The new round-shaped wire includes 126-1320 tape-shaped filaments with triple rotation symmetry, having a good crystal alignment of Bi-2212 in each filament. We refer to the new wire as ROSATwire , (ROtation-Symmetric Arranged Tape-in-tube wire). The ROSATwire fabrication process markedly improved productivity and lowered the cost, and also improved the transport Jc of the wire. The Ic and Jc reached values greater than 340 A and 1000 A mm-2 , respectively, at 28 T and 4 K. Insulated wires of over 400 m length, 2 mm in diameter, are now available and ready for magnet winding. Several solenoid magnets with a 130-160 mm outer diameter and 100-600 mm height are now under fabrication.

Section: Introductionmentioning

confidence: 94%

“…Assuming the J c, oxide for a Bi-2212 grain of a polycrystalline filament in a segment is dominated only by the magnetic field component B p parallel to the c-axis of the grain, the J c,s of the polycrystalline Bi-2212 segment with various crystal alignments can be given by the following equation [9],…”

Section: A Rough Estimation Of the Anisotropy Of J Cmentioning

confidence: 99%

Development of Bi-2212/Ag round-shaped wire and magnet application

Okada¹

2000

“…From the analysis of tensile σ tape (ε) curves at room temperature, a value of ω = 0.02 was estimated in silver sheathed multilayered tapes [54] and a value of ω = 0.008 in monocore tapes, which at 77 K becomes 0.0091 [55]. By comparison of the experimental results with the proposed model, the interfacial shear strength, τ i , between the cores and the sheaths was calculated [53], yielding a debonding value of τ i = 40 MPa.…”

Section: Mechanical Behaviour Of Composite Bscco Tapesmentioning

confidence: 99%

Silver alloys used in composite BSCCO tapes: development of electrical and mechanical properties during manufacture

Navarro¹

2000

The properties of silver alloys used for metallic substrates in Bi-2212 tapes or cladding sheaths in composite Bi-2212 and Bi(Pb)-2223 tapes at different manufacturing steps are reviewed. The values of the electrical resistivity at 77 K and the room-temperature mechanical properties of binary silver rich alloys of Cu, Mg, Mn, Au and Pd and related ternary compositions are summarized and criticized. The strengthening mechanisms have been followed at the microstructural level to systematize the common developments and characteristics. The properties relevant for the powder-in-tube and wire-in-tube fabrication processes, as well as the final mechanical performances of composite tapes are considered. Accordingly, the behaviour of silver alloyed wires and sheets as cast, the variations in intense cold mechanical deformation and the results after long annealing in oxidizing atmospheres are presented. In addition, the interactions between metallic sheaths and superconductor precursor powders by direct chemical reactivity and changes of oxygen diffusivity through the tapes are also analysed. The electrical and mechanical properties up to 10% atomic concentration of alloyed elements are well described with theoretical predictions for homogeneous solid solutions and heterogeneous oxide dispersed alloys.

“…The highest magnetic field value produced by an Nb 3 Sn magnet is actually 21.8 T at T = 1.8 K. Various methods are used for the industrial fabrication of Nb 3 Sn multifilamentary wires: (a) bronze route, by VAC (Germany) [1], Kobe Steel (Japan) [2], Hitachi (Japan) [3], Furukawa (Japan) [4] and Kurchatov Institute, (b) internal Sn route (separate filaments), by IGC (USA) [7], Alsthom (France) and Eurometalli (Italy) [8], (c) internal Sn route (jelly roll), by TWC (USA)/Oxford (USA) [6], (d) Nb tube technique, by Showa (Japan) [9], (e) NbSn 2 route, by SMI (Netherlands) [10] and (f) Nb 6 Sn 5 compound route (Tokai University, Japan) [11]. The observed difference in j c for the various methods is essentially due to the total amount of Sn in the wire, which varies from 13.5 wt% (bronze route) to >30 wt.% (NbSn 2 route), as indicated in table 1.…”

Section: The System Nb 3 Snmentioning

confidence: 99%

“…It was found that B c2 of Nb 3 Sn can be enhanced by ≈4 T after adding Ta or Ti, due to the enhancement of the normal state resistivity ρ n [11,12]. A further enhancement of j c at B > 18 T was later obtained by simultaneously adding Ta (to Nb) and Ti (either to Nb or to the Cu bronze) [1][2][3][4]. The effect of various additives on j c is shown in figure 1.…”

Section: The System Nb 3 Snmentioning

confidence: 99%

Materials for classical and high- superconducting tapes and wires at 4.2 K

Flükiger¹

1997

For the next few years, the classical materials NbTi and will still remain at the centre of interest for the construction of magnets operating at temperatures between 1.8 and 4.2 K. Magnets operating in the persistent mode at fields > 20 T and laboratory magnets approaching 23 T can be envisaged in the near future, based on and wires. The actual situation of critical current densities as a function of the applied field at 4.2 K is briefly reviewed. Considerably higher fields will be produced using insert magnets based on Bi(2212) and Bi(2223) tapes, provided the mechanical properties can be improved.