Abstract
This study investigates the enhancement of corrosion resistance in magnesium-lithium alloys through plasma electrolytic oxidation (PEO) coatings incorporating ZnF(2) via in situ synthesis. By adjusting Zn(2)⁺ concentrations (4-16 g/L) in a zirconium salt-based electrolyte, ceramic coatings with tailored ZnF(2) content, thickness, and porosity were fabricated. The optimal Zn(2)⁺ concentration of 12 g/L yielded a ZnF(2)-rich coating with isolated pores and enhanced densification (inner layer resistance R(i) = 3.01 × 10(4) Ω⋅cm(2)), achieving a corrosion current density (i(corr)) of 4.42 × 10(-8) A/cm(2) and polarization resistance (Rp) of 8.5 × 10(5) Ω⋅cm(2), representing a 354-fold improvement over untreated LA103Z. Higher Zn(2)⁺ concentrations (16 g/L) induced interconnected pores and ZnO formation, degrading corrosion resistance. Long-term immersion (168 h in 3.5 wt% NaCl) confirmed the durability of Zn(12) coatings (mass loss: 0.6 mg), while Zn(4) and Zn(16) coatings exhibited severe localized corrosion. The study demonstrates that balancing Zn(2)⁺ concentration optimizes ZnF(2) passivation and pore isolation, offering a scalable strategy for Mg-Li alloy protection in corrosive environments.