Preparation of intricate nanostructures on 304 stainless steel surface by SiO2-assisted HF etching for high superhydrophobicity

In this work, superhydrophobic surfaces were successfully fabricated on 304 stainless steel via a novel one-step etching and low-cost stearic acid modification treatment. After SiO2-assisted HF etching at room temperature and disposal of reducing surface energy, etched samples displayed a maximum static water contact angle of 162.45 degrees and a minimum sliding angle of 4.8 degrees. The mechanism of SiO2 on the etching process was explored by energy-dispersive X-ray test (EDX) and X-ray diffraction test (XRD). It is the first time to report that the presence of SiO2 has an obvious promotion on the etching process of different diffraction crystal faces of Fe leading to the formation of nanostructures on the microstructure surface. The hierarchical structures make the super-hydrophobicity superior even with fluorine-free modifier. The corrosion and wear resistance test indicate that the prepared super-hydrophobic surface processes excellent corrosion resistivity compared with the untreated stainless steel while maintaining good mechanical stability. The proposed method is scalable, time-saving and low-cost, which shows great potential for industrial applications.