Study of CO2 Laser-induced Thermal Stress Mechanisms on Decorative Soda-lime Glass

In this study, we examine texturing features on soda-lime (SDL) silicate glass bottles achieved using a Carbon Dioxide (CO2) laser with continuous wave power (25 W at 10.6 mu m). SDL glass samples were subjected to irradiation in both static and dynamic modes. In the static mode, exposure time (tau ON) varied from 10 mu s to 2 ms, while the dynamic mode involved scan velocities (line) ranging from 20 mm/s to 3 m/s. Our evaluation focused on engraving rate, fracture morphologies, and damaged zone characteristics. Using optical microscopy and stylus profilometry, we identified three distinct process regimes: partial texturing, full texturing, and material removal. To gain insights into the underlying mechanisms of the process, we developed a 2D axisymmetric thermo-mechanical model using COMSOL Multiphysics (R). This model allowed us to compute the transient laser-induced thermal stress and the relaxation occurring in the viscoelastic state of SDL. Remarkably, our simulation demonstrated a correlation between the tensile cracking threshold of SDL (0.1 GPa) and experimental data. By comapring the experimental and simulation results, we were able to estimate the damaged zone diameter with an accuracy of +/- 3% in the partial texturing regime and an overall accuracy of +/- 8% across all regimes in the static mode.