The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Alberto Baldini - One of the best experts on this subject based on the ideXlab platform.
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Microstructure development in Nb3Sn(Ti) internal tin Superconducting Wire
Journal of Materials Science, 2008Co-Authors: I. Pong, Simon C. Hopkins, B.a. Glowacki, James A. Elliott, Alberto BaldiniAbstract:The authors have studied the phase formation sequences in a Nb3Sn ‘internal tin’ process superconductor. Heat treatments were performed to convert the starting materials of tin, Ti–Sn, copper and niobium, to bronze and Nb3Sn. Specimens were quenched at different points of the heat treatment, followed by metallography to identify the phases present and X-ray microtomography (XMT) to investigate the void volume and distribution. An unexpected observation of the microstructure development was the uphill diffusion of tin during the Cu–Sn reactive diffusion. Some defects likely to affect the Superconducting performance of the Wires were observed. Microscopy revealed the presence of a Ti–Sn intermetallic compound displacing the niobium filaments, and XMT revealed the formation of long pores in the longitudinal direction. Two types of pore formation mechanism, in addition to Kirkendall pores, are proposed. The phase and microstructure development suggests that low-temperature heat treatment (below 415 °C) will have significant influence on optimising the final Superconducting properties.
Maria Maley - One of the best experts on this subject based on the ideXlab platform.
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Materials science challenges for high-temperature Superconducting Wire
Nature Materials, 2007Co-Authors: S. R. Foltyn, Boris Maiorov, Q. X. Jia, Judith L. Macmanus-driscoll, Leonardo Civale, Huaiyuan Wang, Maria MaleyAbstract:Twenty years ago in a series of amazing discoveries it was found that a large family of ceramic cuprate materials exhibited superconductivity at temperatures above, and in some cases well above, that of liquid nitrogen. Imaginations were energized by the thought of applications for zero-resistance conductors cooled with an inexpensive and readily available cryogen. Early optimism, however, was soon tempered by the hard realities of these new materials: brittle ceramics are not easily formed into long flexible conductors; high current levels require near-perfect crystallinity; and--the downside of high transition temperature--performance drops rapidly in a magnetic field. Despite these formidable obstacles, thousands of kilometres of high-temperature Superconducting Wire have now been manufactured for demonstrations of transmission cables, motors and other electrical power components. The question is whether the advantages of Superconducting Wire, such as efficiency and compactness, can outweigh the disadvantage: cost. The remaining task for materials scientists is to return to the fundamentals and squeeze as much performance as possible from these wonderful and difficult materials.
I. Pong - One of the best experts on this subject based on the ideXlab platform.
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Microstructure development in Nb3Sn(Ti) internal tin Superconducting Wire
Journal of Materials Science, 2008Co-Authors: I. Pong, Simon C. Hopkins, B.a. Glowacki, James A. Elliott, Alberto BaldiniAbstract:The authors have studied the phase formation sequences in a Nb3Sn ‘internal tin’ process superconductor. Heat treatments were performed to convert the starting materials of tin, Ti–Sn, copper and niobium, to bronze and Nb3Sn. Specimens were quenched at different points of the heat treatment, followed by metallography to identify the phases present and X-ray microtomography (XMT) to investigate the void volume and distribution. An unexpected observation of the microstructure development was the uphill diffusion of tin during the Cu–Sn reactive diffusion. Some defects likely to affect the Superconducting performance of the Wires were observed. Microscopy revealed the presence of a Ti–Sn intermetallic compound displacing the niobium filaments, and XMT revealed the formation of long pores in the longitudinal direction. Two types of pore formation mechanism, in addition to Kirkendall pores, are proposed. The phase and microstructure development suggests that low-temperature heat treatment (below 415 °C) will have significant influence on optimising the final Superconducting properties.
V.s. Vyatkin - One of the best experts on this subject based on the ideXlab platform.
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Curling Effect in Superconducting Wire
Journal of Physics: Conference Series, 2006Co-Authors: G.l. Dorofeev, V M Drobin, Yu.d. Kuroedov, N M Vladimirova, V.s. VyatkinAbstract:The experimental results of curling effect investigation (sharp increasing of the normal phase propagation speed under influence of the magnetic flux avalanche) in Superconducting Nb-Ti and Nb-Zr Wires are presented. The external magnetic field was imposed parallel to an axis of a sample of a Superconducting Wire by thickness from 0.16 mm up to 0.30 mm without a normal stabilizing covering, the transport current was put, and after initiation of a normal phase on a short part of a sample the normal phase propagation and the magnetic flux avalanche along a sample were registered simultaneously. It was found, that the thickness of the magnetic flux avalanche Lmfa and the thickness of the normal phase front Lnpf (length of the part of a sample engaged by S-N transition) achieves 3 - 4 mm, that is more than 10 diameters of the sample. The heating of a Superconducting Wire by the magnetic flux avalanche is accompanied by increase of the speed of normal phase propagation Vnpp. In a narrow range of change of a transport current the sharp increasing of the speed of normal phase propagation Vnpp up to the speed of a magnetic flux avalanche Vmfa occurs. The further increasing of a transport current is accompanied by reduction of a distance (spacing) between the normal phase and the magnetic flux avalanche. In turn Vmfa increase with increasing of critical current dencity Jc and thickness of a Superconducting Wire. In particular the speeds Vmfa and Vnpp achieve the value 9 - 13 km/s for the Wire Nb-25%Zr by thickness of 0.24 mm with the critical current Jc = 2 - 4 MA/cm2 in magnetic fields 0.5 - 1 T.
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Evolution of thermomagnetic instability along a Superconducting Wire
Physica C-superconductivity and Its Applications, 2003Co-Authors: G.l. Dorofeev, Yu.d. Kuroedov, E. P. Krasnoperov, V.s. VyatkinAbstract:Abstract Propagation of a magnetic perturbation along a monofilament Superconducting Wire under thermomagnetic instability was investigated. In NbTi Wire at temperature T =4.2 K and magnetic field B =0.5–0.7 T the propagation velocity is found V =2.5–3.5 km/s. In NbZr the corresponding value is V =9 km/s.
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Thermomagnetic instability evolution along a Superconducting Wire
arXiv: Superconductivity, 2003Co-Authors: G.l. Dorofeev, Yu.d. Kuroedov, E. P. Krasnoperov, V.s. VyatkinAbstract:Steady state propagation of a magnetic perturbation along a monofilament Superconducting Wire in circumstances of thermomagnetic instability was investigated. At temperature T=4.2K and magnetic field B=0.5-0.7T the propagation velocity is v = 2.5 - 3.5 km/sec in NbTi Wire and this one exceeds a 9 km/sec in NbZr Wire.
Sung Hun Wee - One of the best experts on this subject based on the ideXlab platform.
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high performance Superconducting Wire in high applied magnetic fields via nanoscale defect engineering
Superconductor Science and Technology, 2008Co-Authors: Sung Hun Wee, A Goyal, Yuri L Zuev, Claudia CantoniAbstract:High temperature Superconducting (HTS) Wires capable of carrying large critical currents with low dissipation levels in high applied magnetic fields are needed for a wide range of applications. In particular, for electric power applications involving rotating machinery, such as large-scale motors and generators, a high critical current, Ic, and a high engineering critical current density, JE, in applied magnetic fields in the range of 3 5 Tesla (T) at 65 K are required. In addition, exceeding the minimum performance requirements needed for these applications results in a lower fabrication cost, which is regarded as crucial to realize or enable many large-scale bulk applications of HTS materials. Here we report the fabrication of short segments of a potential Superconducting Wire comprised of a 4 m thick YBa2Cu3O7− (YBCO) layer on a biaxially textured substrate with a 50% higher Ic and JE than the highest values reported previously. The YBCO film contained columns of self-assembled nanodots of BaZrO3 (BZO) roughly oriented along the c-axis of YBCO. Although the YBCO film was grown at a high deposition rate, three-dimensional self-assembly of the insulating BZO nanodots still occurred. For all magnetic field orientations, minimum Ic and JE at 65 K, 3 T for themore » Wire were 353 A cm−1 and 65.4 kA cm−2, respectively.« less
