Effect of additives on the properties of plasma electrolytic oxidation coatings formed on AM50 magnesium alloy in electrolytes containing K2ZrF6

► Many superficial pores with large dimension are filled with coating compounds (MgF2). ► The addition of NH4H2PO4 enhances the passivation effect of the solution on AM50 alloy. ► Properties of superficial pores are greatly influenced by the addition of KF. ► The coating exhibits high corrosion resistance (280 h in 3.5 wt.% NaCl solution).