Bending-Peeling Method to Research the Effect of Lateral Stress on Superconductivity of REBCO Tape at Liquid-Nitrogen Temperature

Rare earth barium copper oxide (REBCO) type materials are widely used in second-generation high-temperature superconductor tapes to carry high current volumes. These tapes can provide high critical currents along with good tolerance to perpendicular magnetic fields. However, REBCO tapes generally use a laminate structure that suffers from low peeling strength among its inner interfaces. Previously, we proposed a bending-peeling (BP) method and applied it to measurement of the interfacial strength of REBCO tapes at room temperature. All samples failed at the REBCO layer at room temperature. In this paper, we used the BP method to perform low-temperature interfacial strength measurements at liquid-nitrogen temperatures. There are two types of failure, where one involves peeling of the REBCO layer and the other involves peeling at the interface between the tape and the epoxy resin. The errors in the BP method were discussed in detail. The superconducting current was monitored during the BP experiment and showed that the effect of out-of-plane tensile stress on the superconducting current was not significant before the breaking of the tape. The degradation in the superconductivity is mainly caused by the structural failure of the REBCO layer.