Synthesis of crack-free monolithic ZrO2 aerogel modified by SiO2

Crack-free monolithic ZrO2 aerogel modified by SiO2 (ZSA) has been prepared for the first time by aging ZrO2 gel in tetraethoxysilane solution and drying in supercritical fluid. The microstructure of ZSA was characterized by scanning electron microscope, Fourier transform infrared spectroscopy and transmission electron microscopy, etc. The influence of SiO2 on the structure and properties of ZrO2 aerogel was studied. The results indicate that hetero-linkage of Zr-O-Si and Si-O-Si band is formed after modified by SiO2. The compressive strength of ZSA is 0.419 MPa, the bulk density is merely 0.19 g/cm(3) and the thermal conductivity of ZSA is as low as 0.021 W/m K.