Residual stresses at the interface between carrier tape and YSZ layer in manufacture of 2G HTS wires

Abstract

Using X-ray diffraction, there were determined the residual stresses on the surface of the AISI 310S stainless steel carrier tape used in manufacture of the second generation high temperature superconducting (2G HTS) wires at the National Research Center "Kurchatov Institute", from delivery to deposition of the main buffer layer YSZ between the tape and the superconducting layer, and the residual stress in the buffer layer YSZ itself. The compressive stress of -0.8 GPa induced by rolling was found on the surface of the tape as-delivered. During processing, it varies from -0.5 to -1.1 GPa. At each stage, its depth distribution was found down to 10 μm, and the residual stresses caused by processing were determined. The residual stress in the YSZ layer deposited using the ABAD technology is compressive and amounts to -3.29 GPa. The layer has a defective single-crystal structure in type to radiation swelling with the unstressed lattice period of 5.1820 Angstrem, 0.9% larger than in ordinary crystal. The results obtained are in agreement with the data of the earlier neutron diffraction study of residual stresses inside the carrier tape. Keywords: residual stress, 2G HTS wires, AISI 310S tape, YSZ layer, YSZ crystal structure, X-ray diffraction.