A novel and cost-effective method for fabrication of a durable superhydrophobic aluminum surface with self-cleaning properties.

A hierarchical superhydrophobic surface is prepared via a two-step boiling water immersion process and anodization of the treated aluminum substrate in a novel hydrophobic electrolyte of aluminum nitrate and stearic acid mixture at room temperature. The immersion time in boiling water had a significant influence on the morphology and durability of the sample. A pseudoboehmite coating is created on the aluminum surface during the boiling process, as revealed by the field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FTIR) spectrophotometer results. The energy-dispersive x-ray spectroscopy analysis confirmed the formation of hydrophobic coating surface after anodization. Also, the FE-SEM images and the atomic force microscopy (AFM) investigation proved the hierarchical nano-and microstructure stem from boiling and anodizing procedures, respectively. The successively boiled and anodized surface exhibited contact angle of about 155˚, sliding and hysteresis contact angles of <5˚ and 2˚, respectively. It also demonstrated a self-cleaning property and remarkable durability.