Modification of Wettability Property of NITI Alloy by Laser Texturing and Carbon Ion Implantation

Abstract

Surface wettability and topography of nitinol alloy samples were modified by means of nanosecond laser treatment and the following carbon ion implantation process. Contact angle measurement, scanning electronic microscope (SEM), X-ray photoelectron spectroscopy (XPS) and surface roughness gage detections were adopted to evaluate the impact of carbon ion implantation on surface wettability, surface topography, chemical composition and surface roughness. The results manifest that the laser treated NITI alloy expressed high hydrophilicity just after laser ablation, however, the hydrophilic performance turned to be high hydrophobicity 20 days later under ambient air conditions. The maximum water contact angle (WCA) for laser treated NITI alloy was 148.2±0.7° with sliding angle an (SA) of 90°. However, the laser ablated wafers followed with carbon ion implantation turned from high hydrophilicity to super-hydrophobicity just about 13 hours after the surface modification with the maximum water contact angle (WCA) of 157±1.3° and the minimum sliding angle (SA) of 3.2±0.7°. It can be found that carbon ion implantation can accelerate transformation process of laser ablated surface from hydrophilicity to hydrophobicity and even to super-hydrophobicity effectively. Otherwise, after carbon ion implantation, the hydrophobic performance had been enhanced and the adhesive capability had been weakened greatly.