An experimental study to characterize a surface treated with a novel laser surface texturing technique: Water repellency and reduced ice adhesion

Abstract

An experimental study was conducted to characterize the laser-textured surfaces fabricated by using a novel nanosecond Laser-based High-throughput Surface Nanostructuring (nHSN) method. While the two-step nHSN approach (i.e., water-confined nanosecond laser texturing and chemical immersion treatment) in producing superhydrophobicity over metal surfaces is described in great details, a throughput analysis of different laser-based surface texturing methods is also performed in the term of Specific Laser Scanning Time (SLST). It is found that the nHSN process significantly increases the processing rate from hundreds of minutes per square inch to seconds in comparison to the existing ultrashort laser-based surface texturing techniques. In order to examine the performance of the novel nHSN-treated surfaces in the term of “water-/ice-repellency”, a series of experiments were performed in the present study to not only characterize the surface structures and wettability of the nHSN-treated aluminum surfaces, but also evaluate the effects of the nHSN treatment on the dynamics of water droplet during the impacting process (i.e., spreading, receding, and rebounding), as well as their capability in reducing ice adhesion strength. It is found that, while the untreated bare aluminum surface and the only laser-textured aluminum surface are hydrophilic with the static contact angle being smaller than 90° and the contact angle hysteresis being larger than 90°, the nHSN-treated surfaces appear to be superhydrophobic with a significantly larger static contact angle (i.e., ~170°) and a much smaller contact angle hysteresis (i.e., ~20°). The superhydrophobicity of the nHSN surfaces is further promoted to “ice-repellency” by the complete droplet rebounding phenomenon in the dynamic water droplet impacting process and the reduced ice adhesion strength.