Mechanical properties of YBaCuO formed on Ni-based alloy substrates with IBAD buffer layers

Mechanical properties of YBaCuO superconducting tape produced by a multi-stage metal-organic chemical vapor deposition (MOCVD) technique have been investigated. It is important for YBaCuO superconducting tape to tolerate stress strain and maintain flexibility in order to be used for electric power applications, magnetic applications, and so on. At this time, we have produced an approximately 0.25 μm YBaCuO layer on a pulse laser deposition (PLD)-CeO₂/ion beam assisted (IBAD)-Gd₂Zr₂O₇/Ni-based alloy substrate by an MOCVD technique, and approximately 4 μm Ag was sputtered on it as a protective layer. The thickness of each layer was approximately 1.0 μm, 1.0 μm and 0.1 mm respectively. Its critical current was about 50 A. The mechanical properties of YBaCuO tape formed on Ni-based alloy substrates with a CeO₂/Gd₂Zr₂O₇ buffer layer will be described. Tensile or compressive bend stress tests were conducted, and normalized critical current and the value n were evaluated. The degradation of its critical current was confirmed not to be in the big problem level in manufacturing applications. In addition, the surfaces of YBaCuO layers were observed by scanning electron microscopy and no crack was observed on them. Next, axial tensile stress tests were conducted and the YBaCuO tape was compared with biaxially textured Ni-3at.%W alloy substrates and YBaCuO layers on Ag substrates. Axial tensile stress characteristics of the YBaCuO tape were confirmed to be much higher than others. The YBaCuO tape was confirmed to have adequate axial tensile stress characteristics for designing a coil which can tolerate electromagnetic force.