Laser Surface Texturing to Realize Micro-grids on DLC Coating: Effect of Marking Speed, Power, and Loop Cycle

In the present study, laser surface texturing was tested with the aim of improving the tribological properties of a diamond-like carbon (DLC) coating. Two experimental campaigns were designed to realize different micro-grids, and to study the effect of marking speed, laser power, and loop cycle. The grid profiles obtained were analyzed using a digital microscope and a laser probe system to measure the track cross section. At the end of the experiments, the authors identified a good-quality track obtained by imposing a marking speed of 300 mm/s, a power of 0.5 W, and one loop cycle. For the identified condition, the presence of defects (such as cracks) on both the coated surface and at the substrate/coating interface was analyzed. Furthermore, the coating nanohardness, adhesion to the substrate, and wear behavior in dry condition were investigated. The results underline how laser texturing can improve the DLC wear behavior (wear tracks lower than 30%) without considerably affecting the other tested coating properties.