EFFECT OF MECHANICAL STIRRING OF YBACUO MIXED POWDER DURING HEAT-TREATMENT ON SUPERCONDUCTIVE PROPERTIES

This paper deals with a new apparatus for the simultaneous processing of mechanical stirring and calcining of superconductive powder materia ls to achieve a simpler process for the fabrication of superconductive oxides. As the first step, the change of the mechanical motion of a p owder bed at elevated temperature was visualized by use of a transpare nt mixing tube. Consequently, it was possible to analyze the effect of temperature on the dynamic motion of the powder bed. From the analysi s, it was found that there was less increase in cohesiveness of mixed powder of Y2O3, BaCO3 and CuO below 400 degrees C. Above this temperat ure, the cohesiveness increased considerably, which produces a negativ e effect of mechanical stirring. Furthermore, the powder calcined in t he tumbling bed at the lowering temperature step of calcining showed b etter superconductive properties than that calcined in the fixed bed.