Abstract
Atmospheric icing on structures and equipment represents a challenge for operation and safety. Passive ice removal by ice-phobic coatings has received much attention over the last decades. The current state-of-the-art methods for quantifying the ice-release properties of such coatings suffer from a range of drawbacks, including poor reproducibility and high complexity test setups. Here, a facile rotational tribometer approach for measuring the static friction between polymeric coatings and ice is presented. The torque necessary to initiate motion at the coating-ice interphase was used as a measure of ice release. For a polydimethylsiloxane-based coating (Sylgard 184), the effects of ice-temperature, normal force, coating thickness, and dwell time (contact time between coating and ice at rest with fully applied normal force prior to applying torque) were established along with the conditions resulting in least data variation. With these conditions, tribology-based friction measurements were carried out on two additional coatings; a two-component polyurethane, and a commercial foul release coating. The outcome of the method, i.e., grading of the coatings in terms of antiicing effect, matched those obtained with a widely used ice adhesion test method based on ice shear adhesion testing. The same trends are revealed by the two methods. However, the findings from the proposed tribology-based method result in consistently lower variation in outcomes and offer more detail on the ice adhesion and friction mechanisms.
Highlights
Ice accumulation on surfaces in cold climates represents a serious challenge from an operational, economical, and safety perspective
Sea Lion Repulse has a break-away torque around 0.43 ± 0.06 mNÆm, indicating superior ice release as compared to Sylgard 184 and 2-component polyurethane (2K PU) reaching this point at 5.7 ± 0.4 mNÆm and 15.34 ± 1.7 mNÆm, respectively
The static and dynamic friction between Sylgard 184 and ice were explored under different conditions using a rotational rheometer-tribology approach
Summary
Ice accumulation on surfaces in cold climates represents a serious challenge from an operational, economical, and safety perspective. Jellinek et al.[4] describe a shear stress apparatus used to detach a block of ice from a flat horizontal surface, yielding a measure of the shear force for ice removal. In this experimental setup, a hollow aluminum mold is placed on a panel coated with a polymeric coating and the mold is filled with water and frozen onto the coating. A pressure gauge is used to measure the peak force obtained when removing the ice from the surface. This methodology, or adaptations thereof, has been frequently adopted in the evaluation of ice adhesion.[9,10,11] Advantages include ease of sample prepara-
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