Effect of nano-Al2O3 addition on mechanical durability of nickel-yttria stabilized zirconia anode support of solid oxide fuel cells

For anode supported solid oxide fuel cells (SOFCs), the strength and durability of the porous cermet support during long-term operation is critical for the reliability of the cells and stacks. The effect of adding nano-Al2O3 on the long-term durability of the mechanical strength of nickel-yttria stabilized zirconia (Ni-YSZ) based SOFC anode supports was investigated in this study. The SOFC anode support materials, Ni-3YSZ (3 mol% YSZ), Ni-8YSZ (8 mol% YSZ), and nano-Al2O3 added Ni-YSZ composites, were subjected to a long-term degradation test at 900 degrees C and 30% humidity in an H-2 environment and after 1000 h exposure, the flexural strength, phase, and microstructural changes were analyzed. The results suggest that the addition of nano-Al2O3 to Ni-3YSZ improves the long-term strength and durability of the cermet while its addition to Ni-8YSZ cermet did not show any significant changes in the strength degradation behavior of the Ni-8YSZ based anode support. Further analysis by SEM and XRD shows that the tetragonal to monoclinic phase transformation in partially stabilized zirconia was suppressed due to the addition of nano-Al2O3 in Ni-3YSZ resulting in improved long-term stability and higher mechanical strength. Replacing the Ni-8YSZ anode support with nano-Al2O3 added Ni-3YSZ might significantly reduce the material cost of SOFCs without compromising long-term strength durability, thus bringing SOFCs a step closer to commercialization.