Tribological properties of titania nanofilms coated on glass surface by the sol–gel method

Ce3+-doped and undoped TiO2 nanofilms with one, three, and five layers were prepared on glass surface by the sol–gel method. The thicknesses were about 40, 120 and 200 nm. Atomic force microscopy analysis showed that many defects existed on uncoated glass substrate surface such as microcracks and microvoids, resulting in high surface roughness. After coating with the TiO2 nanofilms, the microdefects of the glass surface were filled and covered by film materials. With increased film layers and Ce3+ doping, the structure of the TiO2 nanofilms surface became more uniform and compact, and the surface roughness gradually decreased. Nanoindentation and friction wear tests on the samples surface revealed that the surface hardness and friction coefficient of uncoated glass substrate were about 6.8 GPa and 0.37. After coating, the surface hardness of the samples increased and the friction coefficient remarkably decreased. Furthermore, with increased film thickness and Ce3+ doping, the friction coefficient of the sample gradually decreased and its wear-resisting property obviously increased. TiO2 nanofilms coated on the glass substrate surface can be used as protective layers of glass, exerting excellent anti-wear and friction reducing effects.