One-step fabrication of pillar and crater-like structures on titanium using direct laser interference patterning

Direct laser interference patterning (DLIP) is used to create periodic crater- and pillar-like patterns on titanium surfaces. A Nd:YAG laser operating at 532nm wavelength with a pulse duration of 8ns and the ability to control the polarization of each individual beam is used for the laser patterning process. The generated periodic patterns with spatial periods of 5 and 10mm are produced with energy densities between 0.3 and 5.1Jcm-2 with a single laser pulse. By varying the polarization of each interfering beam and the energy density, various forms of the occurring topography are observed due to the different shape of the interference intensity pattern and the solidification front of the molten material at the maxima positions. The characterization of the surface chemistry shows that the laser treatment increases the relative content of alumina in the reactive layer from 36% to 51%. The structural analysis of pillar-like patterned surface shows no changes in microstructure after the laser treatment. Contact angles of 47°±7° down to 6°±4° are measured on both, crater- and pillar-like surfaces which are significantly lower compared to the untreated reference (79°±2°).