In-situ icing and water condensation study on different topographical surfaces

Icephobicity is intrinsically affected by rough asperities and the surface voids provide anchoring points for the ice. The anchor of ice is likely to form on the surface under high humidity conditions. In-situ water condensation and icing observation were conducted to understand water condensation and ice retracting patterns in controlled humidity, pressure and temperature conditions. It was observed that water micro-condensation and icing occurred on rougher surfaces and the water droplets condensed along the surface cracks of the superhydrophobic polydimethylsiloxane (PDMS) based nanocomposite coatings. Further analysis revealed that ice anchoring was present on both aluminum and superhydrophobic coating surface, but it was more severe and intensified on the as-received aluminum substrates. No water condensation or subsequent icing was found on smooth PDMS hydrophobic surfaces due to the incapacity of the smooth surfaces to anchor water drops. It is the first time to validate ice anchoring over retracting ice on different wettability surfaces from in-situ icing observation. Ice adhesion strengths were also measured on the studied surfaces and the results indicated a strong linkage between centrifugal shearing of ice and anchoring mechanism due to surface rough voids, and there was no clear relevancy between ice adhesion strength and the surface wettability or hydrophobicity.