Surface nanotexture variations and applications using high repetition ultrashort laser

Abstract

Modifying surface nanotextures is an increasingly important field that has potential applications because it can achieve useful surface properties. This dissertation aims to contribute to this growing area of research by using an ultrashort pulsed laser with high repetition to develop wetting and reflective properties of aluminum and aluminum alloy surfaces. In wetting properties development, a coating free dual superhydrophobic/superoleophilic surface through laser machining and post-heat treatments in ethanol was fabricated and tested for non-wetting reliability. For this surface, applications such as oilwater separation, ice adhesion, and water disintegration were tested. Also, a method of tuning the wettability between hydrophilic and superhydrophobic states is proposed. The increase in machining depth and stearic acid coating applications were of significant contribution in this process. Quantitative analysis of the change in water droplet contact angle corresponding to surface topography is reported as well. Finally, the effect of varying the defocus distance of the laser beam to create a different appearance on the aluminum surface was investigated. All of these studies were conducted experimentally and obtained nano-textured surfaces were analyzed through imaging and characterization techniques. The results provide a better understanding of the reliability of nanotexturing using laser machining techniques towards intended applications.