Abstract: Photochemical activity of TiO₂ can be reduced through surface coating, which favors to increase dispersiveness, weather resistance and antipulverization. The binary coating process of Si and Al to TiO₂ was studied experimentally. The isoelectic point of TiO₂ in seriflux was measured as pH was equal to 36. Maximum Zeta potential can be got at pH 10 around, which favors to dispersion of particles. Studies on the aggregation rate of Si and Al indicate that, when pHhas a value between 9 and 10, the aggregation rate of silicon acid is small, which favors to form homogeneous and compact membrane, so optimal coating pHvalue is between 9 and 10. According to the difference of 2 p orbital electron binding energy of Ti in XPS before and after being coated, it can be inferred that Si and Al in coating layer combine to TiO₂ surface through chemical bond.

Key words: Titanium dioxide, Coating, Silicon dioxide, Alumina