Characterization of a Commercial Anti-Icing Coating - An effort to further the understanding of the relationship between surface treatment, hydrophobicity and the ability to prevent formation of ice on structures.

Abstract

Icing on structures such as wind turbines, ships and overhead powerline is a major problem in regions prone to sub-zero temperatures. The removal of ice on a surface is both costly and requires constant surveillance. In this thesis, a passive method that reduces the chance of icing without any external influence is tested. A commercial coating made by Jotun is characterized and applied on aluminum samples with different parameters and application methods. The coatings wettability, icing behavior and mechanical properties will be tested and compared to other kind of anti-icing surfaces. The application methods used in this thesis was airbrush, roll and a regular brush. The surface morphology and thickness was studied in the SEM, and the results showed that by using a roll the most reproducible results and uniform coating thickness was achieved. Contact angle measurements revealed no significant difference in wettability of the surfaces, as they all showed hydrophobic contact angles of 100 ± 4°. Efforts of measuring the roll-off angle and contact angle hysteresis were also made, but the adhesion between the substrate and the water droplet was too high. The high droplet adhesion also suggests high ice adhesion, which is unfortunate when it comes to anti-icing. The icing properties of the coating was tested in a climate chamber with adjustable temperature. Several icing tests were performed: the barrier for ice formation, cyclic icing behavior, the freezing of droplets with different volume and the delay of ice formation. The coating had a high barrier for ice formation as the droplet froze at temperatures down to -12.5°C. It also showed that after several icing cycles the icing properties of the coating did not decrease. Scratch testing revealed good adhesion to the surface when the samples were anodized pre-coating. Hardness tests were also done on the samples and the yield strength of the coating was roughly estimated.