Nanosecond laser fabrication of superhydrophobic copper and anti-frost surface on copper.

The frost phenomenon on metal surfaces seriously reduces the system operation efficiency, and the research of robust and effective waterproof protective layer on metal surfaces has become a focus of attention. The ability of superhydrophobic surfaces to stay dry is attractive for frost suppression performance on metal surfaces. However, when subjected to external pressure, the waterproof protective layer is highly susceptible to damage, resulting in the loss of superhydrophobicity. Therefore, a copper surface possessing superhydrophobicity and mechanical robustness was designed and fabricated in this study. The design of robust micro-nano structures on copper surfaces using finite element analysis. The combined modification of the copper surface using nanosecond laser and 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFOTES). Or refilled nano-silica to form the combined surface. The contact angle of the combined surface was 160.3°, and the rolling angle was 1°, both of which helped to obtain superhydrophobicity. The mechanical robustness of the superhydrophobic copper surface was tested by knife, stainless steel wire ball, and tape. The freezing and anti-freezing properties of the droplet on the superhydrophobic copper surface and ordinary copper surface were observed by experiments. The results show that the surface of superhydrophobic copper still keeps superhydrophobicity after repeated mechanical durability tests. When the frost thickness is 0.9 mm (cooling temperature of −7 °C, horizontal placement), the superhydrophobic copper surface (composite surface) has excellent frost suppression performance compared to the ordinary copper surface, and the growth of frost could be delayed by 1.75 times. Meanwhile, the hydrophobicity of the superhydrophobic copper surface remained essentially unchanged after 50 freeze-thaw cycle experiments (a single cooling time of 30 min). We believe that the practical aspects of anti-frost design strategies on the copper surface show a great advantage. • Design and production of the "armor" structure of the copper surface • Freezing of droplets at different stages • Dendritic ice crystals grow at the tips of microdroplets. • The variation of frost layer thickness on different surfaces is discussed. • The composite modified surface has strong frost suppression properties. [ABSTRACT FROM AUTHOR]