Effect of the Growth Conditions on the Optical and Mechanical Properties of TiO2 and Al2O3 Films

The mechanical and optical properties of TiO2 and Al2O3 films deposited by DC reactive magnetron sputtering were analysed as a function of the deposition conditions. 

Two different sputtering powers and three different voltages targets which influence the pressure and the deposition rate were studied. The voltage corresponds to two different percentages of the turn down set point of the hysteresis curve and fully poisoned condition. As their optical application is the main functionality of these coatings, the transparency and the refractive index were investigated. However, the mechanical properties are the key factors for determining the performance of these systems in use. For this, the wear resistance of these coatings was studied through the analysis of the evolution of the friction coefficient with time and the analysis of the wear track. The corrosion resistance has been also analysed through electrochemical studies. The results reveal that there is a clear influence of the studied deposition conditions on the mechanical and optical properties of these films. However, while general conclusions could be drawn for Al2O3 films, for TiO2 films the tendency is not so clear and further work needs to be performed.