Role of synthetic parameters on structure and thermal stability in yttria-stabilized zirconia aerogels

The application temperature and exposure time of lightweight, high performance aerogel insulation is limited by the thermal stability of the aerogel system used. Elevated temperatures cause rapid densification of the porous structures accompanied by increases in thermal conductivity and density. Previous studies have demonstrated the importance of doping concentration to thermal stability in doped metal oxide aerogel systems. The compositional route remains insufficient for stabilizing the pore structures of yttria-stabilized zirconia aerogels at elevated temperatures above 1100 °C. Non-compositionally, modifying synthetic parameters in the aerogel synthesis have been known to change the as dried pore structures. However, few studies have investigated the microstructure evolution of these pore structures under heat treatment. The current work investigates YSZ aerogels prepared via a sol-gel method at 30 mol% YO 1.5 , varying solids loadings and water contents. The results inform the ways in which the aerogel pore structure at high temperatures is sensitive and insensitive to the variation in synthetic parameters. An improved understanding of the relationships between synthetic parameters, as dried structure, and thermal stability will inform future efforts in the design and synthesis of aerogels with thermal stability in extreme environments. Graphical Abstract Solids loading and water content are used to vary the pore structure of yttria-stabilized zirconia aerogels. The evolution of the aerogels is studied to 1000 °C to elucidate changes in thermal stability as a function of as dried specific surface area, pore volume, and pore size Highlights Synthetic parameters of solids loading and water content modify the pore structure of YSZ aerogels. Microstructural evolution of a full factorial set of aerogels is characterized to 1200 °C. Higher specific surface areas contribute to significantly greater densification to 1000 °C. The change in densification with synthetic parameters is small compared to change with composition.