Corrosion and wettability of PEO coatings on magnesium by addition of potassium stearate

Hydrophobic PEO coatings were fabricated in an electrolyte containing potassium stearate. The wetting behaviour of coated samples was studied using dynamic and static contact angle. Also, the corrosion behaviour of the samples was evaluated by polarization method. The dynamic contact angle and hysteresis of the contact angle for PEO coating were evaluated by Wilhelmy plate method. There was an increase in the contact angle of the nanocomposite and traditional PEO coatings when potassium stearate was added to the electrolyte up to 130°. The more hydrophobic coatings, showed more corrosion resistance in 3.5 wt.% NaCl solution. The synergistic effect of potassium stearate and nanoparticles increased the hydrophobicity because of assembling of fatty acid on ceramic powder. Keywords: Magnesium, Coatings, Wilhelmy plate, Plasma electrolytic oxidation, Corrosion