PEDRO J. RIVERO; RAFAEL J. RODRÍGUEZ; SILVIA LARUMBE; MARÍA MONTESERÍN; FRANCISCO MARTÍN; AMADOR GARCÍA; CAROLINA ACOSTA; MARÍA JOSÉ CLEMENTE; PALOMA GARCÍA; JULIO MORA; ALINA AGÜERO
Ice accretion presents serious safety issues, as airplanes are exposed to supercooled water droplets both on the ground and while flying through clouds in the troposphere. Prevention of icing is a main concern for both developers and users of aircraft. The successful solution of this problem implies the combination of active and passive methods and the use of advanced sensors for early detection of icing and monitoring of ice accretion and de-icing processes. This paper focuses on the development of passive solutions. These include advanced anti-icing coatings deposited by a variety of chemical methods including sol-gel, advanced paints based on polyester combined with fluorinated derivatives and applied by electrostatic spray deposition and conventional silicone-based paints modified by adding alumina nanoparticles. Water contact angle has been measured in all cases, demonstrating the hydrophobic character of the coatings. An ice accretion test has been carried out in a laboratory scale icing wind tunnel (IWT) located in a cold climate chamber. Three different studies have been undertaken: ice accretion measurement, durability of the anti-icing behavior after several icing/de-icing cycles and ice adhesion testing by means of the double lap shear test (DLST) methodology. All the studied coatings have shown significant anti-icing behavior which has been maintained, in some cases, beyond 25 cycles. Although these results are still far from any possible application for aeronautic components, they provide interesting insights for new developments and validate the laboratory scale tests.
Link to source: https://www.mdpi.com/2079-6412/10/7/636/htm
Sol-Gel by Dip-Coating
The sol-gel coating was produced by mixing perfluoroalkyl silane (PFAS), aqueous hydrochloric acid (0.1 M HCl) and ethanol. The sol was prepared by mixing PFAS, 0.1 M aqueous HCl and EtOH in a specific molar ratio of 1:5:4.25, respectively, with an aging time of 1 day. Once, the sol-gel has been aged for this period of time, the sol-gel coatings were applied to the reference substrate (6061T6) using a programmable robot ND-R Rotatory Dip coater provided by Nadetech Inc. (Pamplona, Spain).