Both slender pillars and hierarchical structures achieving superhydrophobicity and the comparison of their properties

In this paper, both slender pillars and hierarchical structures on steel substrate including slender pillar ZnO structures on Zn coating, flower-like CuO structures on Cu coating and dandelion-like CuO structures on Cu-Zn coating were obtained. After low-energy modification, contact angles of these three coatings are 157.59 degrees, 160.69 degrees and 157.94 degrees, respectively, and slide angles of them are similar to 6 degrees, similar to 3 degrees and similar to 3 degrees, respectively. Based on classical Wenzel and Cassie theories, by fabricating microstructure models, we theoretically prove that both slender pillars and hierarchical structures can achieve superhydrophobicity. Furthermore, we systematically study the stability of these three superhydrophobic coatings with slender pillars or hierarchical structures using different methods and compare their applications in the field of self-cleaning, oleophobicity, anti-corrosion, and anti-scaling. We discover that these three superhydrophobic coatings with slender pillars or hierarchical structures all show excellent stability and self-cleaning property. The slender pillared superhydrophobic Zn coating presents excellent superhydrophobic property after sandpaper abrasion compared with hierarchical structured superhydrophobic Cu and Cu-Zn coatings. Whereas, the hierarchical structured superhydrophobic Cu coating with flower-like structures shows the best oleophobicity and anti-corrosion property, as well as the hierarchical structured superhydrophobic Cu-Zn coating with dandelion-like structures promises good anti-scaling property.