In situ growth of micro-nano structured black oxide coating on steel with excellent superhydrophobicity and corrosion resistance

Pipeline steels are among the most common engineering materials and are used extensively in various industries. Therefore, it is essential that these materials are hydrophobic and corrosion resistant. Herein, a simple method to prepare a superhydrophobic coating on X65 steel is proposed. Firstly, the black oxide coating (BO) was grown in situ on X65 steel surface, utilizing its morphology advantage to build the micro-nano structure, where they showed a water contact angle (WCA) of 158°. After fluorination, the WCA of the coating increased to 163°. The prepared superhydrophobic samples were exposed to air and salt spray test for a 30-day durability study, where the long-lasting superhydrophobicity of the coating demonstrated its wide applicability. In addition, the coating also exhibited excellent corrosion resistance and self-cleaning property. This work provides a simple and low-cost technique for designing superhydrophobic coatings on steels.