Improvement of mechanical strength of ultralight resorcinol–formaldehyde/silica aerogel by addition of zirconia

Abstract In the present work, RF/SiO 2 aerogels reinforced by zirconia (ZrO 2 ) were fabricated by a sol–gel process combined with N 2 -ethanol supercritical drying. The physical properties and microstructures of the aerogels were investigated by uniaxial compression, X-ray diffraction, N 2 physico-adsorption, scanning electron microscopy, X-ray photoelectron spectroscopy, and infrared spectrum. The compressive strengths of the aerogels were improved obviously with the addition of ZrO 2 . The composite aerogels remained amorphous state even the percentage of ZrO 2 reached up to 6.77 wt%. The pore sizes of the aerogels with various ZrO 2 were hierarchical and the Brunauer-Emmett-Teller surface area increased distinctly with the increase of ZrO 2 . On the contrary, the aerogel particle sizes decreased as the increase of ZrO 2 . In our opinion, the enhanced compressive strengths derive from both of the varied pore structures and the decrease of the particle sizes. Graphical Abstract