Thermo-mechanical coupling effect induced morphology evolution in laser stripping anti-erosion TiN coatings

Laser stripping has emerged as a pivotal technique for repairing anti-erosion coatings in the aviation and armored vehicle industries. This process entails complex thermodynamic interactions that remain incompletely explored. Unraveling the intricacies of the stripping mechanism, especially the evolution of surface morphology, is essential for advancing its industrial utility. This study characterizes the laser stripping effect on TiN anti-erosion coatings using confocal microscopy, scanning electron microscopy, and energy dispersive spectrometer. Notably, at an energy density threshold of approximately 10² J/cm², pulsed lasers are observed to induce a distinctive hydrodynamic surface morphology, marked by parallel asymmetric grooves. This phenomenon is accompanied by a redistribution of surface elements and a decrease in nitrogen content. To dissect the underlying mechanisms, we have developed simulation models that integrate principles of heat transfer and fluid dynamics. These models reveal that the high-temperature decomposition and vaporization of TiN, coupled with the ejection of molten material due to vapor recoil pressure, are central to the stripping process. Additionally, the formation of asymmetric groove profiles is predominantly attributed to the nonlinear superposition effect from overlapping laser spots.