Abstract
The effects of fabrication method and condition on critical current density of Ag sheathed Bi- 2223 superconducting tapes by powder-in-tube method were studied. The highest critical current density (Jc) in the whole process was measured in the repeative heat treatment of 250 hour and mechanical deformation of 2 times. These results are suggested that the high-Tc phase at the heat treatment of 250 hour was superior and the good grain alignment at the mechanical deformation of 2 times was analyzed by XRD pattern. The highest critical current density obtained by pressing method was $1.05\times 10^4A/\textrm{cm}^2$ and $0.78\times 10^4A/\textrm{cm}^2$ in case of rolling method. The multifilamentary wires with 7 and 49 filaments were fabricated to check the applicability of pressing and rolling method for preparing multifilaments wire. The critical current density of 7 filaments tapes prepared by pressing showed $0.45 \times 10^{4}A/\textrm{cm}^2$ and $0.20 \times 10^{4}A/\textrm{cm}^2$ for 49 filaments tapes prepared by rolling.
분말충진법에 의한 Ag/Bi-2223고온초전도선재의 제조방법 및 제조조건에 따른 임계전류밀도를 조사하였다. 전체공정에서 250시간의 열처리 및 2회의 반봅가공 조건에서 임계전류밀도가 가장 높게 측정되었다. 이와 같은 결과는 250시간의 열처리에서 고온상이 크게 성장되었으며, 2회의 반복가공으로 결정입자들이 일방향으로 잘 배열되는 공정조건임을 알 수 있었다. 공정별로는 pressing방법으로 제조한 시편의 임계전류밀도가 $1.05\times 10^4A/\textrm{cm}^2$로 다른 공정에 비해 가장 높았으며, rolling 공정으로는 $0.78\times 10^4A/\textrm{cm}^2$를 갖는 선재를 제조하였다. 7개 및 49개의 세심을 갖는 다심선재를 제조하여 임계전류밀도를 조사하였다. 7개의 다심선재에서 임계전류밀도값은 pressing방법에서 $0.45 \times 10^{4}A/\textrm{cm}^2$ 였으며, 49개 다심은 rolling방법으로 $0.20 \times 10^{4}A/\textrm{cm}^2$를 갖는 선재를 제조하였다.
