YZrO₂-Ni Cermet Processing by High Energy Milling

Abstract:

A new method for SOFC fuel cell anode preparation is proposed where the main difference lies over cermet powder processing by high energy milling. Yttria stabilized zirconia powder and metallic nickel undergo co-milling in a vibratory device employing zirconia bead media. Dispersed and homogeneous powders are therefore obtained. The material is pressed uniaxialy and sintered at 1350°C for 0,5 h in air and under argon and hydrogen. In the former case, partial nickel oxidation occurs before sintering leading to small shrinkage down to 2% and porosity about 38%. Linear shrinkages from 5 to 7% after sintering in both inert and reduced atmospheres were observed not demanding pore-former additives. Conventional YSZ, Ni and NiO powder mixtures were prepared for comparison purpose. The high energy milling process is able to reduce the starting sintering temperature by 130° C besides a higher densification compared to the simple mixtures YSZ+Ni. The excessive sintering and particle coalescence is absent in high energy milled material, where the metal is well dispersed and the microstructure is highly homogenous. The high energy milling process is a promising route to prepare with excellent performance anode materials for SOFC cells.