Fabrication of superhydrophobic surfaces with hierarchical rough structures on Mg alloy substrates via chemical corrosion method

Superhydrophobic surfaces are commonly fabricated by a combination of hierarchical rough structures and low surface energy materials. The hierarchical rough structures of micrometre-scale lump-like structures and sub-micrometre-scale concave-convex structures were firstly and directly fabricated on the surfaces of magnesium (Mg) alloy plates by a simple chemical corrosion. Then, chemical modification with fluoroalkylsilane (FAS) and stearic acid was employed to decrease surface energy. Effect of the composition of chemical corrosive solution on the surface morphology was also studied. Results show that a good superhydrophobic surface on Mg alloy substrates with a 163.4 degrees static water contact angle and 8 degrees rolling angle was obtained via chemical corrosion and FAS modification. The chemicals NiSO4 and NaH2PO2 are both essential to fabricate the hierarchical rough structures needed by the superhydrophobic surfaces.