Heat conduction properties of TiO₂ films irradiated by a continuous laser

The laws of heat conduction play an important role in the application of laser-induced film material modification. In this paper, the thermal effects of titanium dioxide(TiO₂) film surfaces irradiated by a carbon dioxide laser was studied theoretically and experimentally. Firstly, a three-dimensional model of titanium dioxide thin film with a rough surface was constructed using a finite element method and their three-dimensional temperature distribution were calculated. Then, the TiO₂ thin films were irradiated by a CO₂ laser and the effects of irradiation time, power on the morphology, crystal phases and color were analyzed. Simulation results show that the transient temperature field of titanium dioxide irradiated by a CW laser is a Gaussian distribution, which is related to laser power, spot radius, irradiation time and other factors. When the surface temperature is less than the decomposition temperature, the maximum average surface temperature of the film meets the linear relationship with the laser power, and the ExpAssoc nonlinear relationship is satisfied with laser spot radius. Experimental results show that because of laser irradiation, the roughness of TiO₂ thin film decreased and the color of the film changed. Small laser power or short irradiation time leads to small and uneven effective area, on the contrary thermal deformation will occur. Combined with the simulation and experiment results, it is found that the best treatment effect can be obtained when irradiating TiO₂ thin film 10 seconds with a laser with a power of 6 W and a radius of 3 mm.