On the Detection and Removal of Oxides from Laser-Treated Surfaces

Laser texturing is a technique for surface modification widely applicable in various industrial areas, for example, as a substrate pre-treatment for thermal spray coatings. When performed in air, the elevated surface temperature may induce the oxidation of metallic surfaces, which in turn may undermine the coating adhesion. The degree of oxidation depends on the substrate material as well as the processing parameters. This brings about the need for analyzing the oxide content as well as its removal if needed. In the current study, the applicability of two widely available methods for oxide analysis—X-ray diffraction (XRD) and energy-dispersive spectrometry (EDS), is investigated and compared. Furthermore, three types of oxide removal methods—annealing in a reducing atmosphere, gentle laser ablation, and acid etching—were applied, and their efficiency was demonstrated on three classes of materials—stainless steel and W-based and Ti-based materials. Oxide removal by laser ablation was additionally analyzed and correlated with in-process fast heat accumulation temperature measurements.