Conductor development suitable for HTSC cables

Abstract

Five leading European electrical companies have been collaborating within the framework of a BRITWEURAM project with the aim of selecting and developing a production technology for the construction of underground power cables containing high-temperature superconductors. A laser-melting technique was used to form conductors based on the Y-123 phase and the power-in-tube (PIT) and thick-film techniques were used to form (Bi, Pb)-2223/Ag composite superconductors. Thallium-containing superconductors and selected 121 2-phase cuprates were also examined for their suitability as HTS conductors. The most promising results were obtained with (Bi, Pb)-2223 multifilamentary PIT tapes, and two d.c. cable models have been designed, built and tested using these tapes. The best of the prototypes carried 430 A at 77 K in self-field.

Defect structures in MgB2wires introduced by hot isostatic pressing

“…Commercial MgB 2 powder (Alfa Aesar, 98% purity) was first ball milled for 2 h before it was packed into stainless steel tubes. An as-drawn MgB 2 wire with the inner and outer diameters of 0.5 mm and 0.8 mm, respectively, was prepared by the powder-in-tube technique [24,25] and then cut into 4 inch long pieces, sealed at both ends by electric arc welding. The wire was hot isostatically pressed at 900 • C under an isostatic pressure of 200 MPa for 30 min.…”

Phase formation and microstructure development in silver-clad Bi-2223 multifilament composite conductors

“…The silver-clad (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O y (Ag/Bi-2223) composite conductor in long-length multifilament form stands today as the state of the art for practical utilization of highcritical-temperature (high-T c ) superconductivity in electric power applications [1][2][3][4][5]. Achieving the levels of current carrying capacity in the Ag/Bi-2223 composite conductor required for such applications has spurred a substantial development effort to optimize processing strategies and to refine processing parameters [6][7][8][9][10][11][12].…”

“…One path involves the optimization of the oxide-powder (OP)in-tube approach [6][7][8], wherein the precursor is a blend of metal oxides; the second path utilizes a metal powder precursor that consists of a metallic state stoichiometric mix of the constituent metal atoms in lead-doped Bi-2223 [10][11][12]. The methodologies for fabricating Ag/Bi-2223 composite conductor from OP and metal powder (MP) are similar and have been discussed in prior publications [3][4][5]11]. The principal differences between the OP and MP processes are (1) MP composites undergo most of their mechanical deformation while the precursor powder is still in the metallic state [10], § To whom all correspondence should be addressed.…”