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Keywords
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Plasma electrolytic oxidation (PEO), Magnesium alloy, PLA Hybrid coatings, Biomedical, Bioabsorbable
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Abstract
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This study presents the development of novel hybrid coatings composed of plasma electrolytic oxidation (PEO)
and poly(lactic acid) (PLA) on biodegradable ZK60 magnesium alloy. PEO coatings were fabricated using
phosphate-based electrolytes under optimized parameters (0.4 A/cm2, 50 Hz, 50% duty cycle) and treatment
durations of up to 2 min, resulting in porous ceramic layers approximately 70 μm thick, primarily composed of
MgO and Mg3(PO4)2. Subsequent dip-coating with PLA (5 g in 55 mL dichloromethane) effectively sealed the
PEO pores, forming a uniform polymer layer approximately 23 μm thick.Corrosion tests demonstrated that the hybrid PEO + PLA coating substantially improved corrosion resistance.
The sample treated with a 2-minute PEO process followed by PLA coating exhibited a polarization resistance (Rp)
approximately 246 times higher than that of untreated ZK60 after 168 h, and it maintained significant protection
after 13 weeks of immersion (Rp ≈ 6.1 × 104 Ω⋅cm2).Molecular dynamics simulations supported the strong adsorption of PLA on the MgO surface, correlating with
improved sealing performance. Overall, this work demonstrates that PEO/PLA duplex coatings markedly
enhance the corrosion resistance and mechanical stability of biodegradable ZK60 magnesium alloy, making them
highly promising for use in bioabsorbable medical implants.
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