Effects of silver additions on the mechanical properties and resistance to thermal shock of YBa₂Cu₃O_7-δ superconductors

We evaluated the effects of silver (Ag) additions on the mechanical properties and resistance to thermal shock of bulk YBa₂Cu₃O_7-δ (YBCO) superconductors. Various amount of Ag was added to YBCO by two different mixing techniques, i.e. in the form of metallic Ag powder and AgNO₃ powder. It was observed that the bending strength (strength), fracture toughness and resistance to thermal shock of YBCO increased with increasing Ag content, probably due to strengthening mechanisms by the addition of Ag. In addition, YBCO-Ag composites made by mixing with AgNO₃ showed slightly higher strength, fracture toughness and resistance to thermal shock as compared with those made by mixing with metallic Ag powder. The improvement in the resistance to thermal shock is believed to be due to improvements in the strength, fracture toughness and thermal conductivity of YBCO-Ag composites resulting from Ag additions.