TFA-MOD 法による Y 系超電導線材のプロセス開発

抄録

  The recent progress in the development of TFA-MOD for a long coated conductor is reviewed. The TFA-MOD process is expected as a low cost process to realize the power application using coated conductors. On the effort for high I_c values, the drastic improvement of J_c value was realized by the control of the composition in starting material. Although the same composition as a stoichiometric one of YBa₂Cu₃O_y had been used in the previous development, it was found that the shift to Ba-poor composition could make J_c values higher. The composition of Y:Ba:Cu=1:1.5:3 has a peak J_c value in the relation of J_c and Ba-ratio. Consequently, an extremely high I_c value of 735 A/cm-width (@77 K, self field) was achieved. In the development by the batch system, it had been difficult to obtain high characteristics in the long tape. The problem was addressed by the numerical analysis considering gas flow and reaction in the film. Then, a 200 m tape with End-to-End I_c value of 201 A/cm-width was realized. Based on the above mentioned results, a large facility for 500 m was installed.