화학공학소재연구정보센터
Journal of Materials Science, Vol.33, No.5, 1293-1297, 1998
Preparation and critical current density of hot pressed Bi2Sr2Ca2Cu3Ox/Ag tapes
Bi2Sr2Ca2Cu3Ox (Bi-2223)/Ag tapes have been prepared by hot pressing performed at 800-840 degrees C for 12-96 h under 6 or 12 MPa in air. The highest transport critical current density, J(c), is 3900 A cm(-2) at 77 K and 8800 A cm(-2) at 65 K under zero magnetic field, which is observed in tape hot pressed at 820 degrees C under 12 MPa for 24 h twice. The tape has undergone a cold pressing under 260 MPa between hot pressings. J(c) is limited to 120 A cm(-2) in tape hot pressed for 48 h continuously, in spite of total hot pressing time, temperature and pressure all being the same as for tape hot pressed for 24 h twice. It is found that alternate hot pressing and cold pressing is effective in the preparation of Bi-2223 tapes with high J(c), which is determined by the strength of grain coupling. Grain coupling is strengthened in tape hot pressed with an intermediate cold pressing.