Theoretical and experimental approaches to construct highly-durable Sm2O3-containing superhydrophobic surfaces of aluminum alloys

Abstract

The durability of the superhydrophobic surfaces and their robustness to harsh environments are great challenges at present. In the manuscript, Sm2O3 is first predicted by theoretical calculations to be hydrophobic and have strong bonding with the low surface-energy-compound (stearic acid), which can be ideal composition of the superhydrophobic surface coating with high durability and robustness. Then, the rare-earth-salt-solution boiling bath method with the advantages of simply-equipped and time-saving, is proposed to facilely construct such Sm2O3-containing superhydrophobic surface of 7075 Al alloy. The as-prepared surface exhibits a high water contact angle (WCA) of 157.5° and presents hierarchical nanostructures with nanofibers and dandelions-shaped nanospheres. The superhydrophobic surface-coating composes of Sm2O3 and stearic acid as expected. The results of electrochemical impedance spectroscopy (EIS) show that the corrosion resistance of the superhydrophobic surface coating is >400 kΩ cm2, indicating the strong protection for 7075 Al alloy. Other electrochemical studies and various environmental-adaptability measurements towards chemical medium, UV irradiation, high temperature and abrasion demonstrate the high durability of the as-prepared surfaces as well as their robustness to harsh environments. This work should bring new insights of designing and fabricating the superhydrophobic surfaces for practical applications.