From Extremely Water-Repellent Coatings to Passive Icing Protection—Principles, Limitations and Innovative Application Aspects

Abstract

The severe environmental conditions in winter seasons and/or cold climate regions cause many inconveniences in our routine daily-life, related to blocked road infrastructure, interrupted overhead telecommunication, internet and high-voltage power lines or cancelled flights due to excessive ice and snow accumulation. With the tremendous and nature-inspired development of physical, chemical and engineering sciences in the last few decades, novel strategies for passively combating the atmospheric and condensation icing have been put forward. The primary objective of this review is to reveal comprehensively the major physical mechanisms regulating the ice accretion on solid surfaces and summarize the most important scientific breakthroughs in the field of functional icephobic coatings. Following this framework, the present article introduces the most relevant concepts used to understand the incipiency of ice nuclei at solid surfaces and the pathways of water freezing, considers the criteria that a given material has to meet in order to be labelled as icephobic and clarifies the modus operandi of superhydrophobic (extremely water-repellent) coatings for passive icing protection. Finally, the limitations of existing superhydrophobic/icephobic materials, various possibilities for their unconventional practical applicability in cryobiology and some novel hybrid anti-icing systems are discussed in detail.

Reducing Static and Impact Ice Adhesion with a Self-Lubricating Icephobic Coating (SLIC)

“…However, some of these coatings may have additional issues in addition to their mechanical stability. Some studies reported some of these surfaces to perform poorly in environments that were highly humid [18,26,27], at extremely cold temperatures (−15 • C and below) [28], and at conditions besides static ice conditions (i.e., motionless water frozen on a cold surface) or low droplet impact velocities, e.g., less than 10 m/s [29,30]. Additional drawbacks undermining the icephobic properties of these surfaces are described in References [11,28,[31][32][33][34].…”

Laser Irradiation of Super-Nonwettable Carbon Soot Coatings–Physicochemical Implications

“…The laser energy melted the multiple quasisquare-shaped carbon aggregates and merged them into sizeable "soot clumps" with dimensions of a few microns, whereas the protracted heating promoted additional oxidation of the freshly nascent soot agglomerates. Unlike previous studies, it seems there was no loss of material from the nanoparticles, which paves the route for facile single-step modeling of soot-based non-wettable materials with a given morphology, porosity and surface chemistry; features that greatly influence the icephobicity and anti-bioadhesiveness of the interface [4,20]. For that purpose, further experiments encompassing the use of different types of lasers, laser wavelengths, optical lenses and/or soot nanostructures (e.g., those with quasispherical or mixed initial morphology [18]) are mandatory to gain novel insights into the laser-soot interaction mechanisms.…”

Assessment of Icephobic Coatings—How Can We Monitor Performance Durability?

“…In general, icephobic coatings can be defined as materials that hinder ice from forming on surfaces and/or reduce the adhesion of ice to surfaces. Their benefits have been widely discussed [1][2][3][4][5][6]. For aircraft applications, the current approaches mainly aim at combining active ice protection systems (IPS) with icephobic coatings in hybrid IPS to significantly reduce the required heating energy [7,8], improve mechanical deicing measures [9], or to solely use the coatings for rotating parts [10].…”