Preparation and modification of submicron SiO₂ microspheres

With tetraethoxysilane (TEOS) as silicon source, ethanol as solvent and ammonia as catalyzer, submicron SiO₂ microspheres with diameter from 400 nm to 1000 nm were prepared by modified sol-gel method. To obtain good dispersity in oil, trimethylchlorosilane (TMSCl) was used to modify the surface of SiO₂. The modification effect of SiO₂ was measured through hydrophobic character, activation index and hydrophilicity and lipophilicity. The scanning electron microscope (SEM) and microscope analysis show that SiO₂ microspheres have good monodispersity and uniform degree of sphericity, but have weak dispersion in lubricating oil. The hydrophobic character of modified SiO₂ is significantly enhanced, and the activation index is increased as well as the dispersion in lubricating oil is evidently improved. In addition, the modifier amount and modification time have obvious influence on the modification effect.