Preparation and corrosion resistance of hydrophobic zeolitic imidazolate framework (ZIF-90) film @Zn-Al alloy in NaCl solution

A zeolite imidazolate framework-90 (ZIF-90) film with corrosion resistance was prepared on the surface of Zn-Al alloy by solvent thermal synthesis method employing a thinking of "twin zinc source". The crystal structure and morphology of the ZIF-90 film was confirmed by X-ray diffraction (XRD) and secondary electron microscopy (SEM), respectively. The properties of the film, adhesion and the hydrophobicity were tested by the method of cross-cut test and water contact angle measurement. The potentiodynamic polarization curves indicates that the existence of the film decreases the corrosion current density of the Zn-Al alloy, and the plots and appropriate equivalent circuit models calculated from the electrochemical impedance microscope (EIS) measurements reveals that the hydrophobic ZIF-90 surface considerably improves the corrosion resistant performance of Zn-Al alloy.