Wettability analysis of metallic nickel particles on yttria-stabilized zirconia

Solid oxide fuel cells (SOFCs) are a promising energy conversion system known for their high efficiency and low emissions. Ni-based cermets such as Ni–yttria-stabilized zirconia (Ni–YSZ) cermet are widely used as fuel electrodes in this system. Recently, it has been recognized that the wettability between Ni and YSZ is closely related to the aggregation and coarsening behavior of Ni particles, which affects the long-term stability of SOFCs and solid oxide electrolysis cells. However, although there have been wettability studies for molten Ni on oxide substrates, no systematic studies have been reported for Ni particles around 1 μm in size used in actual systems. In this study, Ni particles larger than 200 nm in diameter with stable crystal facets on the surface were prepared on YSZ substrates, annealing under humidified hydrogen atmospheres at 700 °C and 1000 °C. The Ni/YSZ interfacial properties, specifically the contact angle between the Ni particle and YSZ substrate, were quantitatively characterized using the focused ion beam–scanning electron microscope technique.