Measurement of Transverse Tensile Interfacial Strength of REBCO-Coated Conductors

We present a new test method for the accurate measurement of the transverse tensile interfacial strength of rare-earth barium copper oxide (REBCO)-coated conductor (CC) tapes to overcome heavy scattering of data tested using regular test methods. A new composite structure specimen is designed and constructed by solidifying a standard epoxy resin tensile specimen using the three-dimensional printing technology, where a short REBCO CC tape is embedded. The feasibility of the proposed test method is numerically validated through finite element (FE) calculations. Experimental results show that the valid delaminated strength is 2.19-2.51 MPa with the maximum relative error of 7.3%, indicating the elimination of significant scattering in the tested data. By analysing the morphology of the delaminated interfaces and energy-dispersive spectroscopy results, it is discovered that delamination primarily occurs at the interface between the REBCO superconducting layer and the buffer layer and that a small portion of the REBCO and buffer layers peels off. Further error analysis based on the FE method indicates that the tape is more likely to delaminate because of initial defects, whereas the adhesion at the edges of the CC tape due to the redundancy of the epoxy resin increases the resistance of the CC tape to delamination, resulting in a higher testing value than the real one.