MECHANICAL STRENGTH OF HOT-PRESSED BI-PB-SR-CA-CU-O SUPERCONDUCTOR

Bi1.84Pb0.34Sr2.03Ca1.9Cu3.06O(y) bulk superconductors were prepared by hot press sintering at 800-degrees-C at a pressure range from 50 kgf/cm 2 to 200 kgf/cm2 in air for 2 h. The relative density increased with increasing the hot-pressing pressure, and specimens with various relative densities of 70%-90% were prepared. The flexural strength (sigma) at room temperature was related to the porosity (p) as follows: sigma = 138 exp(-2.83 p) (MPa). The flexural strengths of the specimen with p = 0.l were 103 MPa and 113 MPa at room temperature and at 83 K, respectively. The flexural strength tended to increase with decreasing temperature. Anisotropy in flexural strength was observed, which seemed to be due to the grain-oriented microstructure.