Nanomechanical properties and surface wettability of TiO2 films prepared by magnetron sputtering

In this work, TiO2 films were deposited by magnetron sputtering on glass substrate. The effect of sputtering time on the surface wettability and mechanical properties of TiO2 films was investigated. Contact angle measurement was used to analyse surface wettability, and the nanomechanical properties were characterized by nanoindentation. In order to better understand the mechanical properties of prepared TiO2 films, surface morphology of the films was carried out by using atomic force microscopy (AFM). In experiments, the sputtering time varied from 30 to 150 min. The measurement results show that the maximum film hardness was achieved for sputtering time 150 min, with a value of 7.41 GPa. Longer sputtering time resulted in preferable mechanical properties. It was analyzed that the size of the crystal grains on the substrate surface and thickness of the films were increased with the increment of sputtering time, which can be explained the increasing trend of hardness with sputtering time between 30 min and 120 min. The surface roughness decreased with the increase of sputtering time. Moreover, Young’s modulus increased with sputtering time and the maximum value was 72.74 GPa. Hardness and modulus of elasticity of the prepared films were higher than these of glass substrate. This demonstrates that the mechanical properties of the prepared films reached the required for optical applications. The contact angle measurement results show that the prepared films have hydrophilic properties. The maximum contact angle was achieved for sputtering time 120 min with a value of 89°.