Properties of zirconia thin layers elaborated by high voltage anodisation in view of SOFC application

In order to adapt the anodisation technique to SOFC application, zirconium and zirconium-niobium alloys were tested in various electrolytic media and applied potentials (up to 420 V). The elaborated ZrO2 insulating layers were characterised in situ by electrochemical impedance spectroscopy and their thicknesses were determined as ranging up to 1 μm. The effect of thermal annealing treatment of layers prepared in various experimental conditions was investigated by X-ray diffraction (XRD) and solid-state electrochemical impedance spectroscopy in a planar configuration. The effect of the growing conditions on significant parameters such as zirconia crystallite size, zirconia conductivity and activation energy were deduced up to 800 °C. The possibility of using the anodisation process for fuel cell devices is discussed. This study demonstrates that it surely requires the use of more efficient dopants, such as yttria.