The mechanical properties of (Bi, Pb)SrCaCuO (BSCCO) are examined. Particular attention is paid to the effects of porosity on the elastic modulus, the flexural strength, the hardness and the fracture toughness. A study of the effects of porosity on these properties is crucial in developing a clearer idea of the behaviour of BSCCO conductors in service and is a prerequisite for modelling using, for example, finite element techniques. Experiments are carried out which show the effect of pore volume on the mechanical properties and the effect of processing on the fracture toughness. It is found that the critical defect length in BSCCO is surprisingly large and this has important implications for the processing of the materials and for the limits of application.

Bi-2223/Ag/barrier/Ag single-core tapes with various oxide barrier materials (BaZrO3 , SrCO3 , ZrO2 and Al2 O3 ) have been prepared by PIT. The I -V curves and ac susceptibility measurements have been performed for tapes with identical heat treatment history. Young's moduli of these tape samples have been evaluated by three-point bending and the structure of barrier powders and BSCCO cores was analysed by SEM and XRD, respectively. It was found that the shape of I -V curves, the current transfer lengths and the mechanical properties of tapes are all affected by the oxide barrier type and the barrier thickness, as well as by its porosity and uniformity. This is because the oxide barrier controls the oxygen diffusion during the tape heat treatment and simultaneously the HTS phase formation kinetics, its purity and content within the superconducting core. On the base of the results obtained for single-core tapes, two kinds of multifilamentary composite were made and tested.

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