MECHANICAL-PROPERTIES OF BI-2223 TAPES

Fundamental requirements for tapes to be implemented in power transmission cables include flexibility, in addition to current carrying capacity. As a matter of fact, better and better critical current densities are being achieved on BSCCO 2223 tapes worldwide, and even though the best samples are still typically short and in many respects ''exceptional'', it seems that the gap between actual and target values for Jc is becoming promisingly smaller, and first applications closer. It is therefore essential that also the mechanical performances of these intrinsically brittle composites are improved in order to meet the requirements imposed by manufacturing, handling and installation operations. In this work, the mechanical behaviour of 2223 BSCCO tapes made by Powder in Tube was systematically investigated. Stress-strain tensile tests at room temperature and at 77 degrees K, bending tests, and critical current versus strain measurements were carried out on tapes with pure Ag sheath. The results are discussed in terms of a semi-empirical model specifically developed, which takes into account also the thermo-mechanical history of the samples.