Intrinsic dependence of ice adhesion strength on surface roughness

Abstract

The roles of surface roughness on icephobicity including ice adhesion strength have been long debated in icephobicity studies. However, the direct/systematic influence of surface roughness on ice adhesion strength while keeping other surface characteristics such as surface wettability and interfacial cavitation unchanged are seldom reported. In this paper, systematic reduction of ice adhesion strength with the decrease in surface roughness regardless of the surface wettability was demonstrated across all the studied material types, i.e. metallic surfaces and polymeric coatings with different surface wettability. In-situ icing observation studies indicated that the ice did not anchor on smooth metallic surfaces and polymeric coatings but anchored on rough surfaces including superhydrophobic coatings. Effect of surface wettability was argued against the ice adhesion strength based on our results and similar ice adhesion strength was found on materials having different wettability (i.e. hydrophilic and hydrophobic coatings, and surfaces having different contact angle hysteresis). On the contrary, the introduction of low surface energy chemicals (via deposition and/or functionalization) on the surface having similar surface roughness showed a direct reduction of ice adhesion strength. These results indicated the surface roughness is vital in achieving icephobic performance, however, the ultra-low ice adhesion strength could be achieved by the synergetic effect of low surface roughness and low interfacial cavitation (in line with the interfacial correlation factor).