Surface modifications of tin coating by pulsed TEA CO2 laser

Interactions of a TEA CO2 laser, 100 ns pulse, with titanium nitride (TiN) coating deposited on AISI D2 steel, were studied. The energy absorbed from the laser beam is partially converted to thermal energy, which generates a series of effects such as melting, vaporization of the molten material, shock waves, etc. Morphological modifications of the titanium nitride surface can be summarized as follows: (i) ablation of the TiN coating in the central zone of the irradiated area with creation of grainy and cracked features, (ii) appearance of a hydrodynamic structure like resolidified droplets of the material in the periphery region. The process of sample irradiation was accompanied by the appearance of plasma. Color modifications of the sample, upon laser irradiation, indicate possible chemical changes like oxidation. (author)