A novel preform compaction method for fabricating high-performance Y–Ba–Cu–O single-grain bulk superconductor

A novel preform compaction method based on one new type of divisible mould was employed for fabricating single-grain YBCO bulk superconductor, which can complete the preform demoulding process through opening of the mould, rather than pushing the preform out in the regular mould. Thus it has natural superiority on eliminating macro-cracks, which has been proved by the sample surface morphology and the trapped field characterization. In addition, the divisible mould pressed sample exhibits higher levitation force and trapped field properties than the regular mould pressed samples, verifying the potentials of the divisible mould on improving the bulk performance. The optical micrograph results prove the superiority of the divisible mould on eliminating tiny cracks on sample surface. The processing facility and sample reliability brought by the divisible mould should also be emphasized, because the crushing and re-pressing of preform when it presents visible cracks can be omitted and the failed samples with surface cracks will no longer appear. Consequently, the experimental efficiency and stability are both enhanced.

Microstructure Characteristics of YBa2Cu3O7-y Nanocomposite by Shortening the Manufacturing Process

In this study, YBCO bulk was produced using two seeds by placing an additional seed on the upper pellet of the sample fabricated with the ISMG process. It was confirmed that the upper and lower pellets consisting of a–b sector showed a higher number of Y211 particles than those consisting of a–c sector, and that the same tendency appeared at a spot where different interfaces existed. This can be most clearly compared at the center. Finally, it was found that although minimizing the growth of a–c sector is an important goal for fabricating superconducting bulk magnets with high material properties, it is necessary to minimize the size of areas where different interfaces appear. It can be seen that the number of Y211 particles is the smallest inside the boundary surface, and that although they occupied a relatively smaller surface area, large particles agglomerated together.