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The effect of surface pre-treatments on corrosion behavior of cerium-based conversion coatings on Al 7075-T6



Cerium-based conversion coatings were deposited on Al 7075-T6 and characterized to determine the effect of different surface pre-treatments on the corrosion rate and surface morphology. The methods of potentiodynamic polarization and scanning electron microscopy were employed. The experimental results suggest that cerium-based conversion coating is corrosion resistant in NaCl solution. Corrosion current decreased with alkaline cleaning and acid activation of aluminum surface before cerium oxide deposition. Alkaline cleaning and activation improved deposition of cerium-based conversion coatings compared to only alkaline cleaning. Analysis of the surface morphology of the coatings showed that the coatings deposited on the alkaline cleaning and acid treated panels exhibited lower visible cracks compared to coatings on only alkaline cleaned panels.