From infrared to ultraviolet: direct laser interference patterning of additively manufactured titanium alloy using a picosecond laser

Abstract

Medical implants, such as dental screws or hip stems, are made of biocompatible materials so that they can be well integrated into living organisms. For instance, titanium and its alloys offer high biocompatibility and osseointegration, making these materials very common in such applications. Furthermore, the new advancements in additive manufacturing allow to customize the fabrication of implants which are tailored to the patients’ individual needs. Furthermore, it is known that the structural elements with feature sizes in the micrometer range on the implants’ surface play a significant role in the attachment and proliferation of cells. These elements can be fabricated through laser-based texturing methods that offer high flexibility and high throughput. In this work, we explore the potential of fabricating surface microstructures on additive manufactured near-beta titanium alloy parts (Ti-13Nb-13Zr), using the Direct Laser Interference Patterning (DLIP) technique. Hereby, a single laser beam is split into two sub-beams that are subsequently recombined on the substrate surface where they form a line-like interference pattern with a defined spatial period. We combine DLIP with a picosecond-pulsed laser source and investigate the morphologies and surface features that can be created. Thereby, different laser wavelengths were employed, including 355 nm, 532 nm and 1064 nm. The resulting surface textures are analyzed using scanning electron microscopy (SEM) and confocal microscopy (CM), showing different types of laserinduced periodic surface structures (LIPSS), of which the geometry and size depended on the used process parameters.