Study on the High Temperature Pressure Charging Procedure of Bi-2223/Ag Superconducting Tapes

Hermetically sealed samples are required for HIP experiments of Bi-2223/Ag tapes. Otherwise the high pressure gas might penetrate into the inner sample and balance the outside pressure. In this work, a new high temperature pressure charging (HTPC) procedure was proposed for the HIP process of Bi-2223/Ag tapes. Some liquid phase was firstly formed during the normal pressure heat treatment and the gas pressure was then applied directly at high temperature. Dense filaments could be achieved after this new HIP process. It was found the gas inflation temperature (T_add) and dwelling time before inflation (t_add) have some influence on the final microstructure morphology and critical current of HIP samples. A preliminary improvement of I_c of 13% was achieved after optimization, compared with that of normal pressure heat treated samples.