TY - JOUR
T1 - Effects of contact angle hysteresis on ice adhesion and growth on superhydrophobic surfaces under dynamic flow conditions
AU - Sarshar, Mohammad Amin
AU - Swarctz, Christopher
AU - Hunter, Scott
AU - Simpson, John
AU - Choi, Chang Hwan
PY - 2013/2
Y1 - 2013/2
N2 - In this paper, the icephobic properties of superhydrophobic surfaces are investigated under dynamic flow conditions using a closed-loop low-temperature wind tunnel. Superhydrophobic surfaces were prepared by coating aluminum and steel substrate plates with nano-structured hydrophobic particles. The superhydrophobic plates, along with uncoated controls, were exposed to a wind tunnel air flow of 12 m/s and -7 C with deviations of ±1 m/s and ±2.5 C, respectively, containing micrometer-sized (∼50 μm in diameter) water droplets. The ice formation and accretion were observed by CCD cameras. Results show that the superhydrophobic coatings significantly delay ice formation and accretion even under the dynamic flow condition of highly energetic impingement of accelerated supercooled water droplets. It is found that there is a time scale for this phenomenon (delay in ice formation) which has a clear correlation with contact angle hysteresis and the length scale of the surface roughness of the superhydrophobic surface samples, being the highest for the plate with the lowest contact angle hysteresis and finest surface roughness. The results suggest that the key for designing icephobic surfaces under the hydrodynamic pressure of impinging droplets is to retain a non-wetting superhydrophobic state with low contact angle hysteresis, rather than to only have a high apparent contact angle (conventionally referred to as a "static" contact angle).
AB - In this paper, the icephobic properties of superhydrophobic surfaces are investigated under dynamic flow conditions using a closed-loop low-temperature wind tunnel. Superhydrophobic surfaces were prepared by coating aluminum and steel substrate plates with nano-structured hydrophobic particles. The superhydrophobic plates, along with uncoated controls, were exposed to a wind tunnel air flow of 12 m/s and -7 C with deviations of ±1 m/s and ±2.5 C, respectively, containing micrometer-sized (∼50 μm in diameter) water droplets. The ice formation and accretion were observed by CCD cameras. Results show that the superhydrophobic coatings significantly delay ice formation and accretion even under the dynamic flow condition of highly energetic impingement of accelerated supercooled water droplets. It is found that there is a time scale for this phenomenon (delay in ice formation) which has a clear correlation with contact angle hysteresis and the length scale of the surface roughness of the superhydrophobic surface samples, being the highest for the plate with the lowest contact angle hysteresis and finest surface roughness. The results suggest that the key for designing icephobic surfaces under the hydrodynamic pressure of impinging droplets is to retain a non-wetting superhydrophobic state with low contact angle hysteresis, rather than to only have a high apparent contact angle (conventionally referred to as a "static" contact angle).
KW - Contact angle hysteresis
KW - Icephobic
KW - Icing wind tunnel
KW - Superhydrophobic
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U2 - 10.1007/s00396-012-2753-4
DO - 10.1007/s00396-012-2753-4
M3 - Article
AN - SCOPUS:84878254972
SN - 0303-402X
VL - 291
SP - 427
EP - 435
JO - Colloid and Polymer Science
JF - Colloid and Polymer Science
IS - 2
ER -