Effect of Potassium Fluoride (KF) Additive on Morphology and Corrosion Behavior of Plasma Electrolytic Oxidation Films Formed on 5052 Aluminum Alloy

In this study, the 5052 aluminum alloy was coated by plasma electrolytic oxidation (PEO) process in the 12 g.l-1 sodium silicate (Na2SiO3. 5H2O), 2 g.l-1 potassium hydroxide (KOH) using 2 g.l-1 potassium fluoride (KF) electrolytes and also not using it. The formed films in the solutions were compared in the case of KF absence or presence in the electrolyte. The coating surface morphology was inspected using the scanning electron microscopy (SEM). Both coating composition and corrosion behavior were studied by means of X-ray diffraction (XRD) and electrochemical methods. Finally, the experimental results illustrated that having added 2 g.l-1 KF to the electrolyte, the corrosion resistance of the coating was enhanced in addition to improving the film growth rate, despite the fact that there was no significant influence, applying varied voltages.