Study on the Cracking of SiO<sub>2</sub>-TiO<sub>2</sub> Films Prepared by Sol-Gel Method

In this paper, the cracking behavior of sol-gel-derived SiO2-TiO2 films on glass-ceramics substrates is characterized by means of DTA, XRD and SEM. The SiO2-TiO2 films are deposited by sol-gel dip coating with tetrabutyl orthotitanate (Ti(OBu)4) and tetraethyl orthosilicate (TEOS) as raw precursors. The result shows that the cracking of the films is mainly related to the surface cleanliness of the substrate, the thermal expansion coefficients of the film and the substrate, the viscosity of the mixed sol, and the unbalanced stress produced during drying and heating process. The films without cracks were obtained by modifying the composition of sol and controlling the relative humidity and the heating rate of heat treatment.