Papers by Keyword: Silica-Based Aerogel

Abstract: Silica-based aerogels doped with nano-ITO powder were synthesized using sol–gel process followed by supercritical drying. The main factors were studied including dosage of compling agent KH570 and ITO. The result shows that thermal radiation conductivity is 0.02659 W/(m•K) with ITO of 44.44% after 10 g ITO powder is modified with 1 mL KH570. The microstructure and physical characteristic of the SiO₂–ITO aerogels were characterized by FTIR, SEM, TG-DSC and BET. Their specific surface was in the range of 513–775m²/g and their average pore size was mainly 20 nm. Nano-ITO powders are physically embedded by SiO₂ aerogels.

Abstract: In this work, the sol-gel technology is used to produce silica based xerogels and aerogels suitable for insulation applications in Space. The properties of the obtained materials are tailored varying the precursor – Methyltrimethoxysilane (MTMS) or Methyltriethoxysilane (MTES), and the solvent – methanol or ethanol. A two-step acid-base catalyzed synthesis is used, being the obtained gels dried at atmospheric pressure, in the case of xerogels, and in supercritical conditions, for aerogels. Density and thermal conductivity must be made as low as possible for the sought application and only highly porous materials can fulfill this requirement. The obtained xerogels and aerogels, either with MTMS or MTES, show very promising properties for thermal insulation in Space, when methanol is used as solvent. The more suitable materials are obtained with MTMS and exhibit very low density (80-100 kg/m3), very high surface area (~ 400 m2/g) and small pore size (~ 30-40 Å). They also show moderate flexibility and a remarkable hydrophobic character (~ 150º).