Laser-based surface smoothing and subsequently interference patterning of additive manufactured materials to influence their wetting behavior

Additive Manufacturing (AM) processes enable the fabrication of complex three dimensional lightweight parts in a simple way, making these technologies attractive and viable for a wide range of applications in industrial sectors such as aerospace and medical industry. However, it is well known that surfaces of AM components have a relative high roughness level, which can limit their applicability in industrial fields. This study describes the surface modification of AM parts by Direct Laser Writing (DLW) and Direct Laser Interference Patterning (DLIP) to improve the surface quality of additive manufactured specimens made of Titanium 6Al 4V (Ti64) and an Al-Mg-Sc based alloy (Scalmalloy®). The experiments are carried out with an Ytterbium fiber laser and a Nd:YVO4 solid-state laser for DLW and DLIP process, respectively. The DLW laser process enabled the reduction of the initial surface roughness as well as facilitating the fabrication of defined periodical textures with feature sizes in the micrometer range, implemented by DLIP. These textures permitted to control the wettability of the surfaces. The laser treated and non-processed parts are characterized using White Light Interferometry (WLI), Confocal Microscopy (CM) and Scanning Electron Microscopy (SEM). Additionally, the wettability behavior was analyzed through long-term water contact angle measurements over a period of 50 days.