E. Bruneel et al., MECHANICAL AND SUPERCONDUCTING PROPERTIES OF BIPBSRCACUO-PE AND BIPBSRCACUO-MGO COMPOSITES, Superconductor science and technology, 11(1), 1998, pp. 88-93
In this work it is shown that the inherently weak mechanical propertie
s of monolithic high-temperature superconductors can be improved by pr
ocessing the superconductor into a composite. Both polyethylene (PE) a
nd MgO were used to prepare a composite material with BiPbSrCaCuO (BSC
CO) superconductors. Three-point bending tests were conducted on monol
ithic BSCCO, 50 vol% BSCCO-PE and 50 vol% BSCCO-MgO particulate compos
ites. As expected, the PE composites exhibited an increased ductility
in comparison with the monolithic material and a decreased flexural mo
dulus, while the flexural strength remains comparable with that of mon
olithic BSCCO. Although the presence of a resistive percolation path c
ould be demonstrated at and below room temperature, zero resistivity a
t T < T-c was not observed and the magnetic expulsion force diminished
after processing. Magnetic measurements show that this is due to poor
intergrain coupling. In contrast to the PE composites, the BSCCO-MgO
composites can be re-sintered after mixing. This provides an opportuni
ty for the material to regain the intergrain couplings and results in
the recovery of zero resistivity at 110 K and in magnetic expulsion du
e to intergrain currents. Mechanical measurement on the MgO composites
showed a decrease in ductility, an increased flexural modulus and a c
omparable flexural strength.