Improvement of the critical current properties ofin situpowder-in-tube-processed MgB₂tapes by hot pressing

Abstract

We applied hot pressing to in situ powder-in-tube-processed (PIT-processed) MgB 2 tapes. We enhanced the superconducting properties by adding nanometer-sized SiC powder and ethyltoluene (C 9 H 12 ) to the mixed powder. Hot pressing was performed at 100 MPa and 630 • C in an Ar gas atmosphere for 2-10 h. Hot pressing reduced the cross-sectional area of the MgB 2 tapes from ∼0.55 mm 2 for conventionally heat-treated tapes to ∼0.44 mm 2 . This increased the MgB 2 core density from 50% to 70%. Undoped MgB 2 tapes hot pressed for 5 h exhibited a transport J c of 90 A mm −2 at 4.2 K and 10 T, which is about three times greater than that for a tape heat treated without hot pressing. The value of J c for codoped tape hot pressed for 5 h was 450 A mm −2 at 10 T, which is larger than that for codoped tape heat treated without hot pressing (280 A mm −2 ). These results clearly demonstrate that hot pressing is effective in increasing the MgB 2 core density, and hence in enhancing the J c values of PIT-processed MgB 2 tapes.

Strongly enhanced current densities in Sr0.6K0.4Fe2As2 + Sn superconducting tapes

“…The cross-sectional area of the superconducting core in hot-pressed tapes is 0.28 mm 2 , decreased by around 30% compared to that of the rolled tapes. Similar result was also reported in the previous PIT processed MgB 2 tapes 23 . Vickers hardness ( Hv ) measurement was carried out for both tape samples to further investigate the change of core density.…”

Research Progress of Electromagnetic Properties of MgB2 Induced by Carbon-Containing Materials Addition and Process Techniques

“…Agglomeration of the dopants, MgO, and BO x [49,50] in MgB 2, destroys the connectivity and suppresses the J c (H) increment of MgB 2 . To avoid the volume-decreasing problem during Mg-B reaction, high-pressure fabrication process [51][52][53][54][55][56][57] and preparing MgB 2 through diffusion method [33,[58][59][60][61], as reviewed in part 3, have been applied to fabricate MgB 2 with better connectivity. The efforts to increase the J c (H) of MgB 2 are summarized in this paper in an attempt to have a better understanding on the flux pinning mechanism and connectivity of MgB 2 and get some insights into bringing MgB 2 to practical application.…”

An innovating application of PEM fuel cell: Current source controlled by hydrogen supply

“…below 0.25 V. Examples of application are electrical supply for superconducting coils: because of the superconducting nature of such coils, very low voltages (1 mV per wire centimeter [4]) can be applied with very high currents. Besides the oscillations in the current supplied by most generators are detrimental to superconducting coils and even lead to their destruction.…”