| 摘要 |
PURPOSE:To stably produce a large-sized superconductor having strong magnetic levitation force and free from crack and deformation by press-compacting a powdery raw material prepared by a specific method of a prescribed form using a hydrostatic press and growing a superconducting phase by semi-melting thermal treatment. CONSTITUTION:The uniaxial cylindrical press 11 to be used in the present process is composed of a lower mold 12 and an upper mold 13. The raw material powder S1 is prepared by mixing e.g. Y2O3, BaCO3 and CuO at cationic ratios of 1.8:2.4:3.4, calcining the mixture at 920 deg.C for 12hr, putting the calcined product into a platinum crucible after crushing, heating at 1400 deg.C for 20min, quenching the heat-treated product, crushing the obtained block with a copper hammer and incorporating with a prescribed amount of Ag2O or Pt. The raw material powder S1 is filled in the lower mold 12 and preliminarily compacted by pressing with the upper mold 13. The preformed compact S2 is put into an ice-bag made of rubber, evacuated with a vacuum pump and formed with a hydrostatic press 14 to form a compact S3. The compact is placed on a platinum wire in a semi-melting heat-treatment apparatus 15, maintained at about 1100 deg.C for about 30min and cooled in the furnace by a specific method to obtain the objective oxide superconductor S4. |
