Ceramic processing in high-T_c superconductors

摘要

Bulk superconductors are expected to be applied as high current leads and fault current limiters since it is easy to make large parts. It has been found that melt processing is useful for making bulk bodies with grain-oriented microstructures for YBa_2Cu_3O_y [1,2] and Bi_2Sr_2CaCu_2O_y (2212) [3,4]. On the other hand, melt processing is not simply applicable to (Bi, Pb)_2Sr_2Ca_2Cu_3O_y (2223) because of the very small single phase region of 2223 in the phase diagram [5]. Therefore, bulk materials of the 2223 phase should be prepared by solid phase sintering. Ceramic processing (powder preparation and sintering) especially plays an important role for preparing bulk materials of the 2223 phase. In this lecture, the powder preparation, pressure sintering such as hot pressing and sinter forging for the 2223 phase are presented. The relationship between microstructure and superconducting properties are discussed. Mechanical properties are also presented.