Properties Investigation and Microstructures Characterization of a Superhydrophobic Coating on 6061Al Alloy Substrate

In this study, a hierarchical structured superhydrophobic coating on 6061Al alloy substrate is prepared through a simple and cheap way using chemical displacement, vacuum heat treatment, and low-energy modification with stearic acid. The coating has the good superhydrophobicity with a static water contact angle (CA) of 158.3 ± 0.2° and a sliding angle (SA) of 5.0 ± 0.2°. The hierarchical microstructures in the Scanning Electron Microscope (SEM) are mainly and randomly distributed micro-particles and feather-like microstructures. Due to these special structures, the Deionized (DI) water has a very low adhesion on the prepared coating. Especially, when the coating was covered with the fly ashes about tens of microns, the ashes are easy to roll off with a 10 μL water drop from the height of 2 cm. Besides, the specimens put in the DI water for 1 months still possess the good superhydrophobicity, the low adhesion and the excellent self-cleaning. When the specimens were taken out of the oven with 200 °C for 12 h, the coating still remains stable in the properties and microstructures. In addition, the specimens put in the outdoor for 10 months still possess the superhydrophobicity with CA of 157.5 ± 0.3° and SA of 6.0 ± 0.2°.