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The self-cleaning ability of superhydrophobic metal surfaces has attracted extensive attention. The preparation of superhydrophobic material using the coating method is a common processing method. In this experiment, aluminum fins were processed by laser etching and perfluorinated two-step coating. The aluminum surface was modified using a femtosecond laser and 1H,1H,2H,2H- perfluorooctane triethoxysilane (PFOTES). A superhydrophobic aluminum surface with excellent mechanical stability and self-cleaning properties was obtained with the superhydrophobic contact angle (WCA) of 152.8° and the rolling angle (SA) of 0.6°. The results show that the superhydrophobic surface has an excellent cleaning effect compared with an ordinary surface in unit time. Then, a wear resistance test of the superhydrophobic surface was carried out by using the physical wear method. The results show that physical wear had a low influence on the hydrophobic property of the specimen surface. Finally, the Vickers hardness analysis found that the superhydrophobic surface hardness was significantly better than the ordinary surface hardness compared with the superhydrophobic surface hardness. Based on the excellent self-cleaning properties, wear resistance, and robustness of superhydrophobic materials, the laser-etched and perfluorinated superhydrophobic aluminum fins designed and manufactured in this study have broad application prospects in improving the heat transfer efficiency of finned heat exchangers. [ABSTRACT FROM AUTHOR]

There is not a consistent view about the mechanism of wettability alteration during low salinity water flooding. This paper highlights extensive wettability studies to investigate the wettability alteration on mineralogically different carbonates. Contact angle measurements were conducted to characterize wettability changes quantitatively. The results clearly revealed that wettability of carbonate rock surfaces can be altered to a more water-wet condition by lowering water salinity. The trend of the maximum change of contact angle (MCCA) variation with dolomite/calcite content in the rock is fairly linear under the same salinity, which demonstrates that carbonate minerals can affect rock wettability in a way. Also, the higher calcite content in the rock, the greater MCCA, i.e. the stronger effect of LSWF. Besides, the sensitivity of rock wettability to minerals is different under different salinity conditions. When the salinity is in the range of 2384.6 ∼ 4769.2 mg/L, rock wettability is most sensitive to minerals. The analysis of the effect of ion composition showed that the effect of Ca2+ on wettability alteration is greater than that of Mg2+ at room temperature, and with the increase of the content of calcite in the rock, the effect of Ca2+ is more pronounced than that of Mg2+. [ABSTRACT FROM AUTHOR]

This paper uses a new method combining nanosecond laser processing technology and sol-gel to design and manufacture mechanically robust micro-nano structure and modified SiO 2 @PDMS coating on copper substrate. The superhydrophobic composite surface was successfully synthesized with a water contact angle of 159.5° and a sliding angle of 0.5°. The characterization of the prepared superhydrophobic surface #3 (laser-textured@SiO 2 @PDMS protective layer) was studied by optical profilometry, scanning electron microscopy, FT-IR spectroscopy, and X-ray photoelectron spectroscopy. The composite structure of micron/nano and organic/inorganic 3D interwoven network can be observed to improve the hydrophobic, wear-resistant, and compressive properties of the substrate surface. FT-IR spectra fully indicate the presence of PDMS and Si (CH 3) grafted onto SiO 2 particles on the copper surface, and the presence of Si O and Si C detected by XPS fully proves the FT-IR results. In addition, self-cleaning, wear resistance, anti-icing, corrosion resistance, and NaCl deliquescence behavior were evaluated. The results show that surface #3 can efficiently remove contaminants within 200 s. In the anti-icing experiment, the delayed icing time and ice adhesion strength of surface #3 are 3.33 times and 1.99 % of that of the ordinary copper surface, respectively, which can make the icicle slide easily. In the electrochemical test, the corrosion current density decreased by an order of magnitude, and the corrosion inhibition efficiency reached 90.57 %. Based on its excellent self-cleaning, mechanical robustness, anti-icing, and anti-corrosion properties, we believe that the composite modified surface of the laser-textured@SiO 2 @PDMS protective layer designed and manufactured in this study is expected to be used in engineering fields such as refrigeration heat exchangers. • Design and manufacture of an "armored" structure on copper surfaces. • This coating exhibits excellent self-cleaning properties and mechanical stability. • The composite surface has ultra-low water adhesion and ice adhesion strength. • The mechanism of anti-icing and anti-corrosion properties are explained. [ABSTRACT FROM AUTHOR]

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]