Frost and Ice Transport on Superhydrophobic Copper Surfaces with Patterned Micro- and Nano-Structures

Abstract

Texture and wettability have an important influence on fogging, frosting, and icing on a metal surface. We fabricated micro- and nano-structure patterns on a copper surface by wire electrical discharge machining and subsequent chemical oxidation. By controlling the manufacturing process, three types of microstructure were machined: gratings, pillars, and pyramids. We then studied the wetting performance of the superhydrophobic surfaces with one-tier texture or two-tier texture and the corresponding transport of water in different phase states including fog, frost and icing and their melting processes. Two-tier roughness on the copper effectively improved the superhydrophobicity and retarded the formation and growth of frost. More importantly, these surfaces showed a long delayed icing time, even after several heating and cooling cycles, displaying good resistance to frost and icing. This can be well explained by an understanding of classical nucleation theory, Brown coalescence, and one-dimensional heat and mass transport.