Electrochemical studies on corrosion performance of LY12 aluminum alloy/ passivation film/epoxy coatings composite electrodes
LY12铝合金/钝化膜/环氧涂层复合电极的腐蚀电化学行为

The corrosion performance of LY12 aluminum alloys/passivation film/epoxy coatings in NaCl solution was characterized by electrochemical impedance spectroscopy (EIS). The results showed that the impedances of composite electrodes continuously increased with increasing of immersion time. In the beginning of immersion, the diffusion impedance emerged in the impedance spectroscopy of composite electrode, which was considered to result from the mass transport behavior of solving products of passivation film prepared on metal substrates. The observation of scanning electron microscope (SEM) indicated that the chromate conversion film presented the obvious crack morphology on metal substrates, which is favourable the solved chromate for penetrating through the film and passivate the metal substrate surface. This may be the possible reason of the continuous increase in impedance in composite electrodes.