Silica aerogel paper honeycomb composites for thermal insulations

Applicability of super-insulating silica aerogel materials for thermal insulation is still restricted by limited mechanical strength. We report on a systematic improvement of silica aerogels in respect to shrinkage, density and thermal conductivity by varying sol-gel parameters as the molar ratios of TEOS:EtOH:H₂O or the hydrolysis time. The received silica aerogels can be combined with paper-based honeycomb structures to improve the mechanical strength. We successfully manufactured such silica aerogel paper honeycomb composites. The challenges in the preparation are the must to prevent shrinkage of the silica aerogels during synthesis, to avoid cracks by supercritical drying, and to get a perfect bonding at the paper–silica interface. The composite materials are characterized with respect to their compression modulus, thermal conductivity, and flammability.