Improving the hydrophilicity of metallic surfaces by nanosecond pulsed laser surface modification

The objective of this work was to investigate the surface wettability alteration of the titanium and 316L grade stainless steel by nanosecond pulsed laser processing method. For this purpose, various processing conditions were studied extensively. Different analyses, including the study of the surface morphology, free energy, oxidation, and roughness changes, were assessed in correlation with wettability. It is shown that laser processing in air up to 1 J/cm² laser fluences enhances the surface roughness which in turn promotes the hydrophilicity. The shape and distribution of the created surface structures are also effective in this regard. On the other hand, the surface free energy as well as oxygen content also increases significantly on the laser-irradiated surfaces. According to these results, it is more logic to conclude that all of these cooperative chemical and physical changes are involved in increasing the surface wettability and causing it to be more hydrophilic.