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Microstructural characteristics and corrosion behavior of cerium oxide conversion coatings on AA6063



Cerium-based conversion coating was deposited on aluminum 6063 and its corrosion behavior was studied. Corrosion resistance was investigated at different pH in 3.5 wt% NaCl solution by means of electrochemical impedance spectroscopy, potentiodynamic polarization, and surface techniques. The coated samples showed a significant decrease in corrosion rate. The coating obtained by 600 s immersion covers uniformly the alloy surface. Electrochemical impedance data shows that with increasing immersion time, the charge transfer resistance of aluminum increased. Surface morphology and its chemical composition were analyzed by means of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). SEM images in agreement with the electrochemical results indicated that aluminum surface was not completely covered after short immersion time. The EDS analysis confirmed the presence of cerium oxide on the aluminum surface and the cerium content was increased with increasing immersion time.

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