EFFECT OF AG-PARTICULATE ADDITION ON PROCESSING, MICROSTRUCTURE, AND PROPERTIES OF MGO-WHISKER-REINFORCED-BULK BPSCCO HIGH-T-C SUPERCONDUCTOR COMPOSITES

In associated papers [Y. S. Yuan, M. S. Wong, and S. S. Wang, J. Mater , Res. 11, 8-17 (1996); J. Mater. Res. (1996, in press)] it has been s hown that weak thermomechanical properties of a bulk monolithic high-T -c superconductor (HTS) can be improved by introducing strong ceramic whiskers into the HTS ceramic materials, In this paper, we report a fu rther study of incorporating Ag particulates, (Ag)(p), in a bulk monol ithic BPSCCO and in the MgO-whisker reinforced BPSCCO composite, Effec ts of the (Ag)(p) addition on processing, microstructure, and supercon ducting and mechanical properties of the bulk monolithic BPSCCO and th e (MgO)(w)/BPSCCO composite are investigated. The results indicate tha t the highly ductile Ag particulates promote densification of the BPSC CO matrix phase in the composite during hot pressing. The microstructu re of the HTS composite with the (Ag)(p) addition is similar to that i n the HTS material without the (Ag)(p), The (MgO)(w)/BPSCCO composite with 10% (by weight) Ag particulates has been shown to possess excelle nt superconducting properties. The (Ag)(p) addition to both the monoli thic BPSCCO and the (MgO)(w)/BPSCCO is found to increase appreciably t heir fracture toughnesses, but has little effects on mechanical streng ths of the materials. Quantitative relationships have been established among solid-state processing variables, HTS phase developments, micro structures, and superconducting and mechanical properties of the (Ag)( p)/BPSCCO and the (MgO)(w)/(Ag)(p)/BPSCCO HTS composites.