Facile synthesis of superhydrophobic three-metal-component layered double hydroxide films on aluminum foils for highly improved corrosion inhibition

A simple hydrothermal method was presented to obtain various superhydrophobic ZnMgAl layered double hydroxide films on aluminum foils (AF) with excellent corrosion inhibition. The as-prepared metal surface showed excellent superhydrophobicity, corrosion inhibition and mechanical robustness. Scanning electron microscopy (SEM) results showed that uniform and dense films were obtained on the aluminum surface when the pH of the reaction solution was maintained at 12, which showed the highest roughness and best superhydrophobicity compared with the samples fabricated under different conditions. The static water contact angle (WCA) for the prepared surface was observed to be about 159 degrees. The phase structure of the as-prepared LDH films was characterized by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that the flower-like homogeneous micro/nanoscale film nanosheets were composed of ZnMgAl LDHs with various metal mole ratios. The enhancement of the corrosion resistance of the ZnMgAl LDH films was confirmed by electrochemical corrosion tests. The corrosion current densities of bare AF and ZnMgAl LDH covered aluminum in 3.5% NaCl solution are 3.981 x 10(-5) A cm(-2) and 1.778 x 10(-6) A cm(-2), respectively, which showed the highly improved corrosion resistance of the LDH films. The high charge transfer resistance observed from the results of electrochemical impedance spectroscopy (EIS) tests further indicated the anticorrosion properties of the ZnMgAl LDHs. The excellent corrosion resistance is favorable for the potential applications of ZnMgAl LDHs for a significantly long period of protection for the coated aluminum substrate.