1991 年 26 巻 6 号 p. 495-501
The influence of an intermediate cold isostatic pressing (C. I. P.) on the superconducting properties of Bi-Pb-Sr-Ca-Cu-O superconducting bulk has been investigated, and heat input per a pair of the bulk between 4.2K and 77K has been evaluated. The critical current density (Jc) was improved by the effect of C. I. P. and sintering after initial sintering. The maximum transport Jc at 77K under zero magnetic field was indicated as 580A/cm2, and that at 4.2K under zero magnetic field was indicated as about 3, 500A/cm2. The reasons for these improvements are the formation of the high Tc single phase with a fraction of low Tc phase and the higher density increasing of microstructure. The heat input per a pair of the bulk between 4.2K and 77K has been indicated to be about 60mW and also considered to be of nearly one-third lower than the level of 100A DC condition for the optimum designed current leads with helium vapor cooling.