High temperature tensile strength of ultrathin 3YSZ tapes: An experimental study combining Weibull theory and fracture mechanics

High temperature electrolysis (HTEL) has several advantages compared to other types of solid oxide cell (SOC) technologies, including an increased efficiency at high temperature when combined with an exothermic process. To reduce costs, increase lifetime and improve scale up production of electrolyte supported SOCs, an important property is the mechanical stability of the cell, which is provided by the ceramic electrolyte. In this work, the tensile mechanical properties of ultrathin (t = 90 μm) 3% yttria-stabilized zirconia electrolytes were measured at room and operating temperature (T = 850 °C). In-situ nanoindentation was also performed to study the 3YSZ local mechanical properties at room and high temperature. The calculated characteristic tensile strength and Weibull modulus allowed the evaluation of mechanical properties with improved reliability compared to the previously reported values in the literature, deriving from the substantially larger tested material volume. An extensive fracture analysis revealed porosity or particle inclusions at the fracture origin. The defect size and strength relation showed a deviation from linear elastic fracture mechanics, identifying the presence of subcritical crack growth.