Hydrophobic Aluminum Alloy Surfaces Fabricated by Imprinting Process and Their Wetting State Evaluation Using Air Layer Images

Abstract

This paper presents an imprinting process, which can impart hydrophobicity to aluminum alloy surfaces, and a method for analyzing the wetting states of solid surfaces with multi-scale structures. Electrical discharge textured (EDT) surface and groove pattern molds were produced by electrical discharge machining (EDM) and wire electrical discharge machining (WEDM), respectively. The aluminum surfaces having hierarchical patterns were produced by imprinting processes using both EDT surface and groove pattern molds. The groove patterns with various pitches from 400 to 1,000 µm were applied to the mold designs, so that the effects on static water contact angle (WCA) could be analyzed. Results showed that the hydrophobic aluminum surface with WCA of 117.6° can be achieved through the facile imprinting process. In addition, a wetting state analysis method using air layer images was proposed. Using this method, it was demonstrated that the surface wetting state can be accurately analyzed by combining the air layer images and the theoretical models such as the Cassie–Baxter, and Wenzel models.