关键词: 高温超导体, 热处理, 微观结构, 电流密度

Abstract: The effects of heat treatment on the microstructure and the critical current density J_C of Ag-sheathed BiPbSrCaCuO(2223) superconducting tapes prepared by the powder-in-tube technique are investigated.The microstructure of oxide layer and the J_C values of the tape at 77K are strongly dependent on the heat treatment condition(temperature,time and cooling rate).The experimental results show that the optimum heat treatment temperature and cooling rate to maximize J_C values of the tape are in the range about 840-850℃ and 50-100℃/h respectively, and the J_C values of the tape increase with the prolongation of heat treatment time from 50h to 200h.If the temperature is higher than 850℃, the high Tc phase will partially go to melt.On the other hand, if the temperature is lower than 840℃,the high Tc phase might not completely form. Both of them reduce the J_C values of the tape. If the cooling rate is less than 50℃/h or greater than 100℃/h,the J_C values of the tape will also decrease.

Key words: high-temperature superconductors, heat treatment, microstructure, current density