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Re superhydrophobic - TODAY:

Superhydrophobic Coatings as a new Strategy for Energy Saving Anti/de-icing Systems

C. Antonini*1, M. Marengo1, A. Amirfazli2
*1Department of Industrial Engineering, University of Bergamo,
viale Marconi 5, 24044 Dalmine, Italy, [phone].
2Department of Mechanical Engineering, University of Alberta,
Edmonton, AB, T6G 2G8, Canada.

2011

http://www.ilass2011.org/upload/1084_paper_sqlvqm.pdf

Abstract
The application of superhydrophobic coatings for the development and optimizations of anti/de-icing systems for
aeronautics or wind turbines appears to be a promising strategy to combat icing. Whereas majority of studies
dealing with coating has focused mainly on reducing ice adhesion forces, to more easily remove ice once it is
formed, in this study we focus on promoting the shedding of liquid water as a way to reduce the total amount of
water present on the surface, before it can freeze. The shedding of liquid water is promoted by reduction of airfoil
surface wettability, which is measured by contact angle and contact angle hysteresis of a drop in contact with
the surface. In our previous study [1] we already proofed that a coating strategy, used in combination with an
anti-icing system, allows to significantly reduce heating power required to avoid ice formation in the collection
zone and to reduce ice accretion. In the present work, we focus on two new aspects: first, the assessment of coating
strategy performance when the heating system operates intermittently, as a de-icing system; second, the optimization
of heating power distribution on the wing, for reducing heating power requirements. Tests were performed
in a small icing wind tunnel (IWT) facility (air velocity of 28 m/s, air static temperature of -17°C, and
mean volumetric diameter range 50-750ìm). A segment of a NACA0021 airfoil that had electrical heating at its
leading edge was used. The test article as described allows for installation of interchangeable segments in its
midsection. Three different insertion segments with variable wettability, from hydrophilic to superhydrophobic,
were used. Results show that a coating strategy is effective also when used in combination with a de-icing system,
as it is effective with an anti-icing system.

http://www.siliconinvestor.com/readmsg.aspx?msgid=28714519

http://www.siliconinvestor.com/readmsg.aspx?msgid=28714515

At Ross Nanotechnology, we have developed a super hydrophobic coating that completely repels water and heavy oils. Any object coated with our NeverWet™ coating literally cannot be touched by liquid. Any liquid placed on this coating is repelled and simply rolls off without touching the underlying surface. Not only is this amazing to see, but it solves a myriad of problems.

http://www.neverwet.com/
LotusShield is a patented nano/micro-scale materials coating that provides superior water repellency and protections for almost any surface.

http://www.lotusleafcoatings.com/coating-products/superhydrophobic-coatings/

http://www.siliconinvestor.com/readmsg.aspx?msgid=28714105

Inspired by the Lotus leaf and the desert beetle, our process uses solgel chemistry (Brinker and Scherer, Sol-Gel Science: The Physics and Chemistry of Sol-Gel Processing, Academic Press 1990) to make a coating solution, which upon simple evaporative drying, develops a nanoscopically rough silicon dioxide surface decorated with hydrophobic ligands. This combination of surface roughness and surface chemistry confer to the surface superhydrophobic properties as seen in Figure 3, where a water droplet is measured to have a 172o contact angle.

Importantly, this superhydrophobic coating process can be applied to any surface regardless of composition and can be applied to complex geometries. Additionally, by nanoscale control of the surface roughness, our coating exhibits nearly perfect optical clarity (see Figure 4). Optical transparency is a must for applications like self-cleaning, non-fogging displays, avoiding ice formation on optical elements, and protecting culturally important statuary from acid rain corrosion. Ultra-high contact angles combined with optical transparency and the ability to coat to arbitrary surfaces are distinguishing features of this technology.

http://www.sandia.gov/research/research_development_100_awards/_assets/documents/2008_winners/Superhydrophobic_SAND2008-2215W.pdf

http://www.siliconinvestor.com/readmsg.aspx?msgid=28714187