Optimization of CIP process on superconducting property of Bi-2223/Ag wires composite bulk

In order to improve superconducting property of Bi-2223 superconductor bulk, 5 mm in width, 22 mm in length and ca. 2 mm in thickness, silver (Ag) wires of 0.4 mm in diameter were composed in the bulk. The composite was made by stacking alternately Ag wires and the calcined powder. The pressed sample was sintered at 840°C for 50 hours in air. After treatment with a cold isostatic press (CIP) as an intermediate pressing, the sample was sintered again. With 6 times of CIP processing, the maximum critical current density (J_c) at 77.3 K of the sample composed with twenty-four Ag wires was obtained to be 950 A/cm². SEM and EPMA observation results showed that highly c-axis oriented and densely structured Bi-2223 plate-like grains could be formed around the interfacial region between the superconducting oxide and the metal Ag.