Monitoring of the corrosion of YSZ by impedance spectroscopy

Abstract

Mixtures of yttria-stabilized zirconia (YSZ) with a soda-lime glass and different types of alumina were co-fired at high temperature (1500 °C) before characterization by impedance spectroscopy and scanning electron microscopy (SEM). The roles of location and average grain size of the alumina phase on the composite electrolyte properties were evaluated. The electrical response of the composite materials was found to be strongly influenced by the presence of a YSZ-glass interface where the motion of oxygen ions is blocked. The formation of this interface can be easily identified because of a typical relaxation frequency, much lower than those corresponding to bulk or grain boundary behavior in YSZ-based materials, or to the glass phase alone. Zirconia-based cells were also covered with a top layer of glass, and afterwards fired and electrically characterized by impedance spectroscopy. With increasing firing time at constant temperature, the relaxation frequency of the intermediate frequency arc moves from typical YSZ grain boundary behavior to lower values near to those found for the YSZ-glass interfacial response in YSZ+glass or YSZ+glass+alumina composites. This is a strong indication of the potential of impedance spectroscopy in monitoring the electrolyte corrosion process.