Preparation and characterization of silica hollow microspheres and tribological behavior

PS-SiO₂ composites and SiO₂ hollow spheres were successfully prepared by using polystyrene (PS) particles as templates and tetraethoxysilane as precursors. The silica shells were coated on the surfaces of template via electrostatic interaction. Fourier transform-infrared spectroscopy, thermo-gravimetric analysis, transmission electron microscopy, and scanning electron microscope measurements were used to characterize these hollow silica spheres. Their tribological properties were also investigated. The results show that large quantity of monodispersed PS-SiO₂ composites with a diameter of about 0.7 μm can be obtained in this process. After the calcination treatment, the templates were removed and SiO₂ hollowspheres were perfectly retained. The friction experiment was made at UMT-2 (CETR) and it could be concluded that the base oil with 2 wt% prepared SiO₂ nanostructures had better friction reduction than those with pure oil. The friction coefficient can be reduced to about 0.058 in low load.