Mechanical stabilization of BSCCO-2223 superconducting tapes

摘要

A system to provide mechanical stabilization to high temperature BSCCO-2223 superconducting tape by laminating 0.081 mm thick, spring hard, copper foil to both sides with lead-tin eutectic solder has been successfully optimized. This system has been applied as a method to create a strong, windable composite from pure silver BSCCO tapes with a minimum of critical current (I(sub c)) degradation. The (open quotes)as received(close quotes) conductor is evaluated for physical consistency of width and thickness over the 3000 meters that were later strengthened, insulated and wound into a demonstration coil. Electrical degradation in the strengthened tape as a result of lamination was found to average 24 percent with a range from 4 to 51 percent. This was less than the degradation that would have occurred in an unstrengthened tape during subsequent insulation and coil winding processes. Additional work was performed to evaluate the mechanical properties of the strengthened tapes. The copper can double the ultimate tensile strength of the pure silver tapes. Additionally, pure silver and dispersion strengthened silver matrix tapes are laminated with 0.025 mm thick copper and 304 stainless steel foil to investigate minimization of the cross sectional area of the strengthening component. The stainless steel can increase the UTS of the pure silver tapes sixfold. Metallography is used to examine the laminate and the conductor. Mechanical properties and critical currents of these tapes are also reported both before and after strengthening. The I(sub c) is also measured as a function of strain on the laminated tapes.