Ultrafine Monodisperse Spherical Silica Composite Particles Preparation

By means of SEM, TEM, laser scattered particle analyzer, etc., the formation mechanism of ultrafine SiO2 particle was studied. It was found that at the initial stage, the SiO2 particle consisted of some minicrystal, but after the initial stage the SiO2 particle was formed by some soluble aggregated substance growing on the surface of the early particle.It was demonstrated that the reaction temperature, solvent, concentration of the reactants and catalyst, ageing time affected the particle size and distribution. By controlling these factors or feeding TEOS step after step, monodispersed and spherical ultrafine SiO2 powder could be prepared. The average particle size was from 50nm to 2um.A compounding particle was prepared by coating monodispersed and spherical ultrafine silica particles with titania which obtained by the hydrolysis of Ti(SO4)2. The TiO2/SiO2 particle was characterized with scanning electron microscope (SEM), infrared spectroscopy and XPS. It could be saw from the photo of SEM that the compounding particle was still spherical, and there were some TiO2 on the surface of SiO2 particle. Ti-O-Si was formed between TiO2 and SiO2, and this was confirmed by FT-IR analysis.