Characterization of warpage behaviour of Gd-doped ceria/NiO–yttria stabilized zirconia bi-layer samples for solid oxide fuel cell application

To predict the warpage behaviour of an anode-supported half-cell of a solid oxide fuel cell (SOFC), a viscoelastic analysis has been made for a system with Gd-doped ceria (GDC) and NiO–yttria stabilized zirconia (NiO–YSZ) bi-layers. The viscoelastic properties of each component at 1573 K are measured by discontinuous sinter forging (for GDC) and continuous sinter forging (for NiO–YSZ) techniques. Using the measured uniaxial viscosities and the viscous Poisson ratio, the warpage during the co-firing of a GDC/NiO–YSZ bi-layer is calculated for the continuum mechanical models of Cai et al. and Kanters et al. The warpage predicted by the two models, in particular that of Cai et al., is shown to be in good quantitative agreement with the experimental observation. This result demonstrates that the warpage of bi-layer samples during co-firing can be suitably predicted when the viscoelastic properties of each component are properly measured and estimated. The present investigation also provides a useful methodology for optimizing the design of planar asymmetric half-cells for the SOFC industry.