Search

Laser surface texturing is a powerful tool to fabricate functional surface textures, whereby their morphology and cross‐sectional profile greatly depend on laser parameters such as pulse duration and fluence. In this work, the authors fabricate well‐defined groove‐like textures on stainless steel by laser surface texturing using different pulse durations ranging from nano‐ to femtoseconds, while keeping structural parameters such as depth and periodicity fairly constant. By doing so, the influence of the pulse duration on the resulting cross‐sectional profile of the textures and its subsequent impact on the tribological response are assessed. Reciprocating ball‐on‐disk tests and computational fluid dynamic simulations with Abaqus are used to evaluate the tribological performance of the as‐fabricated textures. Their results demonstrate that the use of laser pulses with different pulse durations induce changes in the resulting cross‐sectional profiles with the formation of rims/bulges well as the occurrence of recast phenomena and debris accumulation for nanosecond laser pulses. Decreasing the pulse duration significantly reduces the heat affected zone and the thermal damage, as well as avoided the formation of rims/bulges. Reciprocating ball‐on‐disk tests demonstrated that the differences in the cross‐sectional profiles have a significant influence on friction and wear behavior of the textured surfaces. The tribological properties of surface textures fabricated with different laser pulse durations ranging from nano‐ to femtoseconds are investigated. The influence of the pulse duration on the textures' profile and its impact on the tribological response are assessed. Their results demonstrate that laser pulse duration has a significant influence on the topography of surface textures and thus the frictional response. [ABSTRACT FROM AUTHOR]

Recently and interestingly, experiments show that the CO 2 laser conditioning can significantly increase the laser-induced damage threshold (LIDT) of fused silica optics, but its underlying mechanism has not been clearly revealed. This Letter reports the experimental studies on the evolution of the intrinsic point defects and intrinsic ring structures on the surface of fused silica optics under the CO 2 laser irradiation. The laser conditioning can effectively reduce the intrinsic defect contents in the surface layer of mechanically processed fused silica. However, the suppression effect of defects can be affected by the initial surface state. If there are micro-cracks on the component surface, the effect of the laser conditioning would be limited. The evolution of the intrinsic ring structures indicate that most of the intrinsic defects tend to recombine as short (Si-O)n ring structures during the laser healing of the micro-fractures. The observed recombination behavior and suppression of the intrinsic defects can help find out the reason for the increase of the LIDT of the fused silica optics.