A wear-resistant superhydrophobic surface on Q235 steel prepared by electrospark deposition and electrochemical etching

The special wettability of superhydrophobic metal surface endows it with considerable application potential in various fields, but the vulnerability of its surface structure is the biggest obstacle to its extensive application. Herein, a robust superhydrophobic structure on steel surface was prepared using electrospark deposition and electrochemical etching. Electrospark deposition greatly improved the wear resistance of the steel surface, and electrochemical etching further prepared the hierarchical micro-nano-superhydrophobic structure. Besides, the morphology, element distribution, chemical composition, roughness and wettability of the superhydrophobic surface were characterized by SEM, EDS, XPS, FTIR, roughness meter and contact angle meter, respectively. The results showed that the superhydrophobic surface had high roughness and that the structure was beneficial to air storage. Electrospark deposition successfully introduced elements to form alloys on the surface of steel and improved the surface wear resistance. After modification with myristic acid, the prepared rough surface was equipped with excellent superhydrophobicity, and the contact angle of water reached 159° ± 2°. The robustness of the superhydrophobic surface was carefully investigated by carrying out different tests over items including linear friction, sand impact, tape peeling, knife tip scratch, knife edge scratch and hammering. It had been verified that the surface of superhydrophobic steel prepared by electrochemical etching was fragile, and the use of electrospark deposition before electrochemical etching contributed to the higher-level robustness of the superhydrophobic surface structure. In addition, the contact angle of the superhydrophobic surface remained unchanged at a temperature of 250 °C for 24 h, and it showed excellent self-cleaning performance in both chalk and dirty water tests.