Fabrication and characterization of bulk BSCCO(2212)-SrSO4 composites by melt casting process

We fabricated 2212-SrSO4 composites by the melt casting process and evaluated the effect of melt flowing on the critical current (I c) by using two different pouring methods, i.e., the conventional vertical casting and the tilt casting methods. It was observed that the 2212-SrSO4 rod processed by the tilt casting method had a higher I c value than that processed by the vertical casting method. This improved I c is considered to be related to the more homogenous microstructure due to the laminar flow of the melt. In addition, we evaluated the variation of the I c with the SrSO4 content. The I c value was found to be significantly dependent on the SrSO4 content: the I c of the 2212 increased as the SrSO4 content increased and reached a peak value (260 A at 77 K) at an SrSO4 content of 6 wt.%, and then decreased when the SrSO4 content was further increased. This increase is probably due to the lower porosity, larger grain size and stronger texture, resulting from the enhanced diffusion kinetics. The possible causes of the variation in the I c with the SrSO4 content based on the microstructural observations were discussed in detail