Facile electrodeposition of superhydrophobic aluminum stearate thin films on copper substrates for active corrosion protection

Abstract

A facile aluminum based superhydrophobic thin films were electrodeposited by mixing aluminum isopropoxide (AlOx) with stearic acid (SA) onto the copper substrates via one-step method. The energy dispersive X-ray spectroscopy (EDS) attenuated total-reflectance Fourier Transmission infrared spectroscopy (ATR-FTIR) were used to confirm the presence of Al, C, and O as well as COOAl and CH bonds in the thin film. The water-roll off properties were analyzed by measuring the contact angle to study the superhydrophobic nature of fabricated films. Results show that superhydrophobicity with the water contact angle of 161 ± 1° and the contact angle hysteresis of 2 ± 1° were obtained with respect to the AlOx/SA molar ratio of 0.33. The morphology of the fabricated thin films consisted of uniform porous structures with surface roughness (rms) of 3 μm on the copper substrate. The addition of stearic acid plays an important role for the superhydrophobic property. Furthermore, the thin films and their anticorrosion behavior were investigated using 3.5 wt% corrosive aqueous NaCl electrolyte solution. The polarization resistance of the thin film is found to be 962 kΩ·cm2 as characterized by Tafel. Similarly, impedance value of 10 MΩ·cm2 was obtained from Electrochemical Impedance Spectroscopy (EIS). A simple fabrication of water-repellent superhydrophobic aluminum-based coating endues extremely high active in corrosion protection.