Fabrication and assessment of anode supported SOFCS doped with aluminum titanate via electrochemical and non-destructive micro-indentation testing

Abstract

Ceramic-metal (cermet) composites are the most promising electrochemical anodes for commercial implementation in solid oxide fuel cells (SOFC). Recent advances at MSU in cermet formulations utilizing aluminum titanate (ALT) dopants in nickel oxide (NiO)-yttria stabilized zirconia (YSZ) anodes has shown substantial performance gains in degradation rates as well as mechanical behavior when evaluated in low power density electrolyte supported cell (ESC) geometries and bulk anode forms through modulus of rupture and equibiaxial flexure. The benefits associated with ALT are due to the formation of secondary phases of nickel aluminate and zirconium titanate in NiO-YSZ cermets that form during processing. Cermet modulus of rupture studies are rigorous, can span multiple months, and requiring hundreds of samples when studying the effects of both thermal and redox cycling on SOFC anodes to achieve statistically significant results. The use of non-destructive methods such as micro-indentation to examine the strength and toughness of doped and differently processed cermet anodes can rapidly speed up the analysis of mechanical properties including the mechanical support characteristics of higher power density anode supported cell (ASC) geometries targeted by industrial SOFC developers. The aim of this study was to examine non-destructive micro-indentation testing in evaluating cermet anode materials in both oxidized and reduced state in direct contrast with traditional destructive methods. Extending the current state of ALT anode doping by utilizing these rapid assessment methods, this work examines mechanical properties degradation and fracture toughness under multiple thermal and redox cycles. Additionally, this work details the framework for cell fabrication methods that were developed to process ASCs with state of the art 5 micrometer electrolytes for the first evaluation of ALT doping of SOFCs in this high power cell configuration.