High thermal stability of SiO2–ZrO2 aerogels using solvent-thermal aging

The ZrO2–SiO2 aerogels (ZSA) with varied particle size were synthesized by solvent-thermal aging (STA) method. The effects of STA temperature (60, 110, 170 and 210 ​°C) on microstructure and thermal stability of the ZSA were investigated by SEM, TEM, FT-IR and XRD. The ZSA-210 presents the minimum shrinkage (9.3%), and it has the largest retention values of specific surface area (59.2%) and pore volume (90.8%) after 1000 ​°C heat treatment for 1 ​h. Compared with the aerogels prepared by traditional aging, the ZSA prepared by STA can maintain a low thermal conductivity (0.0285–0.0328 ​W ​m−1 ​K−1) while improving the compression strength (~1.28 ​MPa, 10% strain). STA can restrain viscous flow between ZSA particles by particles growth and skeleton coarsening; and STA can restrain the growth of t-ZrO2 by forming more Si–O–Zr bonds in the system. The work will be meaningful for the design of super thermal insulation materials with high thermal stability and low thermal conductivity.