Atmospheric drying preparation and microstructure characterization of fly ash aerogel thermal insulation material with superhydrophobic

• Fly ash can be prepared silica aerogel with excellent performance. • The silica aerogel of hydrophobic angle is 146°. • The silica aerogel of thermal conductivity is as low as 0.0234 W/m·K. In this paper, silica aerogel is prepared cheaply by atmospheric drying method using coal fired fly ash, a solid waste produced by power generation. By means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), pore size and surface area analysis, X-ray diffraction (XRD), Fourier transform infrared spectrum(FT-IR), laser confocal Raman spectrum(LRS), differential scanning calorimeter(DSC), thermogravimetric analyser(TG) and coefficient of thermal conductivity meter and other modern characterization methods, to explore the surface morphology, microstructure, chemical bond state, thermal stability, chemical stability and thermal conductivity of silica aerogels, and the effect of acid amount on its performance are analyzed. The results show that fly ash can prepare silica aerogel with high purity, high specific surface area, low thermal conductivity, and good chemical stability. When the volume ratio of sulfuric acid to calcining mixture is 10, the silica aerogel prepared has the best performance, the thermal conductivity is as low as 0.0234 W/m·K, the surface is super hydrophobic, the hydrophobic angle can reach 146°, the limit service temperature is 400°C, and the specific surface area is 809.923 m 2 /g.