Elastic Properties, Equibiaxial Strength and Fracture Toughness of Electrolyte Material for Solid Oxide Fuel Cells (Sofcs)

Abstract

The mechanical properties of single and multi-layer tape-cast 8mol% yttria-stabilized zirconia (YSZ) were characterized up to 800°C in air. Elastic properties were determined by Impulse Excitation and Resonant Ultrasound Spectroscopy as a function of porosity and temperature. Equibiaxial strength was determined by the Ring-on-Ring test method and the results ware analyzed using Weibull statistics.Fracture toughness was determined by double torsion. It was found that the elastic moduli, characteristic strength and fracture toughness of YSZ samples decrease with testing temperature between 20°C and 600°C, but that they increased slightly between 600°C. and 800°C. It was also found that the characteristic strength of multi-layer YSZ samples is always lower than that of single-layer samples and that the difference in characteristic strength values between single and multi-layer samples decreased with temperature. Fractographic analyses suggest that a possible explanation for the significantly lower biaxial strength of multi-layer samples is the occurrence of interfacial defects in multi-layer samples.