Omniphobic Etched Aluminum Surfaces with Anti-Icing Ability

Abstract

In this work, omniphobic surfaces are developed by combining chemical etching and surface modification of aluminum. In the first step, hierarchical micro/nanostructuring is carried out by chemical etching. Thereafter, a perfluoropolyether is grafted onto the corrugated aluminum substrate, decreasing its surface free energy and turning the system omniphobic. The morphology and chemical composition of the developed surfaces are characterized. We observed a low affinity toward liquids, regardless of their chemical nature and surface tension. The surface shows superhydrophobic properties with a water contact angle of 160°and simultaneously strong oleophobic properties with a hexadecane contact angle of 141°. Furthermore, these omniphobic surfaces significantly delay the freezing time of water droplets to 5100 s, which is about 20fold of the freezing time on pristine aluminum (260 s), and they even inhibit ice growth by repelling the incoming droplets prior to ice nucleation.

A General Strategy towards Superhydrophobic Self-Cleaning and Anti-Corrosion Metallic Surfaces: An Example with Aluminum Alloy

“…Such surface can be realized through the synergistic effect of two main factors: modification with low-surfaceenergy materials and creation of a certain type of hierarchal micro-nanostructure. Up to now, numerous effective approaches have been developed to prepare superhydrophobic surfaces, including sol-gel [34,35], template [36], electrospinning [37], hydrothermal synthesis [26,38], laser fabrication [39], etching [40,41] and electrochemical processes [42]. The superhydrophobic surfaces with micro-nano structures on the metallic substrates have also been reported in some previous work [6,16,[43][44][45][46][47][48][49].…”

“…Grignard et al [58] achieved superhydrophobic Al surfaces by electrospinning of the fluorinated diblock copolymer solution, which is made of poly(heptadecafluorodecylacrylate-co-acrylic acid) (PFDAco-AA) random copolymer and polyacrylonitrile (PAN). Palenzuela et al [40] produced superhydrophobic Al surface through ferric chloride solution etching and functionaliza-tion of perfluoro(polypropyleneoxy)methoxypropyltrimethoxysilane (PFPE). Among the mentioned approaches, some are easy, fast and economical while a few still face certain limitations, and it is necessary for the improvement towards some issues such as poor scalability, sophisticated procedure, high cost of chemicals and long processing time.…”

Extended Gibbs Free Energy and Laplace Pressure of Ordered Hexagonal Close-Packed Spherical Particles: A Wettability Study

“…Preparation of a solid surface with positive pressure and positive slope (as explained) can lead to a superhydrophobic surface with WCA greater than 150°. Designing superhydrophobic surfaces with special roughness and surface tension, with positive pressure and positive slope, has been investigated and applied in many fields, such as self-cleaning, , medical applications, wind turbine, energy saving, electric power line, photovoltaic cells, anti-icing, , changing the heat transfer performance, controlling the frictional pressure loss in tubes or channels, etc.…”

Anisotropic Ice Adhesion of Micro-Nano-Structured Metal Surface by a Femtosecond Laser

“…Ice coating on the surface of a metal has been a lot of trouble to many fields such as aviation, ship, and electricity. − Currently, mechanical or chemical deicing methods, which are commonly used, are often inefficient, energy-consuming, costly, or even harmful to the environment. In order to solve these problems, metal surfaces with passive icephobic characteristics of micro-nano structures have been widely studied in recent years. − An icephobic surface with hydrophobic wettability is considered to be one of the most attractive strategies for preparing icephobic materials. − For the low ice adhesion strength on the hydrophobic micro-nano-structured surface, the generally accepted explanation is that the water droplets freeze in the Cassie–Baxter state, and the air is retained under the droplets, which act as a stress concentration effect and reduce the actual contact area between the ice and the solid surface, and thus the ice adhesion strength is reduced .…”