Influences of heating rate on the nano-porous structure of silica aerogel

Silica aerogel shows great potential in the relevant high-temperature applications, such as furnaces, tubes, and bricks. The related studies on addressing its behaviors under high temperatures are critically needed. Through this study, the effects of heating rate on its high-temperature behaviors of silica aerogel granule with a size of 100 mesh were addressed experimentally, including density, pore size distribution (PSD) and so on. It was known from the experimental results that the skeleton density increases under a relatively higher heating rate, while the densification, shrinkage, and fractional density show a decreasing trend. The mean coordination number of tested silica aerogel was obtained within a range of 2.016–2.034 contacts. The confusing of the primary particle was found mainly occurring at the sample surface for all the tested samples. It was also known that the diameter of the primary particle increases from 44 to 71 nm when the heating rate increases from 5 to 20 °C/min, but for the particle, it shows a decreasing trend. After the heating processes, the pore model of the sample was changed from cylinder to slit-shaped. A fast heating rate was found to promote the transfer from the Si–OH group to the Si–O–Si group.