The Effect of Fabrication Variables on Filament Quality of Mono and Multifilamentary BSCCO-2212 Round Wires
Round silver-sheathed Bi2Sr2CaCu2Ox Mono and Multifilamentary Wires (19, 31 and 361 filaments) were made with and without extrusion and by drawing. Hexing the monofilaments at a smaller size led to better filament quality in the multifilamentary composites compared to hexing them at a larger size. Wires with a small Ag:BSCCO ratio (< 1:1) could not be drawn reliably with 20% reduction in area per pass but could be drawn at 10% per pass. However, using 10% reduction per pass in the multifilament stage created incipient center-burst defect problems and the final filament quality was degraded. Wires made from finer BSCCO powder had higher critical current density (Jc). The Jc of the better quality composites increased with decreasing filament diameter. Extrusion of multifilament stacks at room temperature and small reduction ratios (3:1) produced much better filament quality than extrusion at 250° C and larger ratios (10:1).
KeywordsReduction Ratio Filament Size Filament Wire Filament Composite Filament Diameter
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