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In the present research, automotive windshield samples were successfully coated with SiO 2-TiO 2 nanostructure layer using the sol-gel technique for self-Cleaning and photocatalytic applications. This procedure resulted in transparent, crack-free, self-cleaning, nanostructure SiO 2-TiO 2 films. To prevent the thermal diffusion of the sodium ions from the glass substrate to TiO 2 layer, the SiO 2 layer was pre-coated on the glass by the sol-gel method. The coated samples were dried for 48 hour at room temperature to allow slow solvent evaporation and condensation reactions due to rapid sol-gel reaction of titania precursor. Then, the samples were annealed at 100℃ for 30 min and at the final temperature (500℃ and 700℃) for 30 min immediately. The crystalline structure, surface morphology, photocatalytic activity and hydrophilic properties of the films were investigated using XRD, SEM, FE-SEM, UV-Vis spectrophotometer and contact angle measurement, respectively. The FE-SEM surface morphology results indicate that the particle size increases from 19 to 42 nm by increasing the annealing temperature from 500℃ to 700℃. Likewise, XRD illustrate the crystal anatase and rutile as main phases for SiO 2-TiO 2 films annealed at 500℃ and 700℃, respectively. Increasing heat treatment temperature from 500 to 700℃, decreases the photocatalytic activity and inversely increases of the contact angle of the films.

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It is known that silica sol-gel coatings microstructure depend on the components of the sol. In order to develop different microstructures of the silica coatings and comparing their optical properties, a variety of silica sols were prepared which were consist of TEOS, water, catalyst and changing the solvent content, at room temperature. Prepared glass surfaces were coated with silica sol using a dipping technique, with constant withdrawing rate. Prepared coatings were investigated by field-emission scanning electron microscopy (FE-SEM) and UV-Vis. spectroscopy. Transmittance spectra showed that silica coatings featured a distinct increase of substrate transmittance at all wavelengths (400-1100 nm). The result indicated that by increasing the solvent content, the porosity of coating increased and the coating was more densified therefore the silica coating transmittance increased by 3-4% points. FE-SEM showed that the nanostructure silica coating grain size were estimated ~20-40 nm.