In this article, the influence of the water vapor concentration on structural changes of SiO2 aerosol nanoparticle agglomerates during tempering was studied. The presence of water vapor in the carrier gas was shown to strongly accelerate the kinetics of sintering. While dry sintering at temperatures between 1100°C and 1500°C generated aggregates only, the addition of water to the process yields individual, completely coalesced nanoparticles at a temperature of 1300°C. Furthermore, depending on the water vapor concentration and temperature of the process, evaporation and condensation processes could be observed, leading to bimodal size distributions. The results prove the significant role of the water concentration in high temperature synthesis of silica and may be used to improve the control over morphology and specific surface area in these processes.
The effect of water vapor on the particle structure and size of silica nanoparticles during sintering
V. Goertz, F. Weis, E. Keln, H. Nirschl, M. Seipenbusch
Aerosol Science & Technology, 2011, 45, 1287-1293