Interfacial properties and structure stability of Ni/Y2 O3-ZrO2-TiO2 cermet anodes for solid oxide fuel cells
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Ceramics of the ternary system Y2O3-ZrO2-TiO2 (YZT) and Ni/YZT cermets are evaluated in terms of application as anode electrodes in a Solid Oxide Fuel Cell. Wetting experiments in liquid Ni/YZT systems show that the increase of TiO2 content in the ceramic phase improves the bond strength at the metal ceramic interface, due to the reduction of the interfacial energy. Ni(40 vol%)/YZT cermets are exposed at 1000°C for up to 1000 h in reducing atmosphere and exhibit an improved long term stability regarding to the electrical conductivity and the microstructure compared to the “state of the art” Ni/8YSZ (yttria(8 mol%)-stabilized zirconia) cermet. This is explained by the enhanced adherence at the Ni/ceramic interface, which suppresses the agglomeration rate of the Ni particles. The improvement of the interfacial properties diminishes the TEC values of the Ni/YZT cermets constraining the thermal expansion mismatch between the cermet anode and the 8YSZ electrolyte in the SOFCs.
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