Synthesis and characterization of silica aerogel and its composite materials

摘要

We report a novel method to synthesize silica aerogel composite by fibers using low cost sodium silicate as precursors, ceramics fibers as reinforced skeleton (15wt %), via ambient pressure drying process. To minimize shrinkage during drying, surfaces of wet silica aerogel were modified using trimethylchlorosilane (TMCS) via one-step solvent exchange and surface modification. Composite SiO aerogels exhibited stable hydrophobic (contact angel about ~135° in room temperature), low density (0.196 g/cm), high specific surface area (630 m/g) and large pore volume (2.6cm/g). Thermal conductivities at desired temperatures were analyzed by transient plane heat source method. Thermal conductivity coefficients of composite aerogel monoliths changed from 0.0266 to 0.0572 W/(m·K) as temperature increased to 400°C, revealed an excellent heat insulation effect during thermal process. Our work will be helpful to provide a general guide on how to commercial exploitation composite aerogel monoliths, which possessing 7.2cm diameters and have desirable structure and properties using in heat insulation environment.