Aggregate structural changes in silica aerogels with temperature

The structure of silica aerogel is a unique three-dimensional nanoporous consisting of silica nanoparticles. It has a potential for using in high temperature range due to the non-combustion of the skeleton and the excellent insulation performance. However, the structure of silica aerogel will collapse under high temperature resulting in the decrease of its performance. This paper introduces a parameter s for describing the structural change in silica aerogel aggregates with increase in temperature. The authors propose a new formula based on the scaling theory for calculating s. The gel was formatted by off-lattice diffusion-limited cluster-cluster aggregation of identical spherical particles in a cubic box. The Monte Carlo method was used to determine the formula factors. The authors calculated the temperature dependence of the particle diameter, concentration and specific pore surface area of the silica aggregates of 500 primary spherical particles in the temperature range of 300-900 K. The simulation results are in good agreement with the experimental results.