Improvement in corrosion and wear resistance of glass sealed PEO coating on the AZ31B Magnesium alloy

Magnesium alloys are prone to corrosion, limiting their applications as biodegradable implants because of their poor corrosion and wear resistance in corrosive environments. This study investigates the effect of the incorporation of pulverized glass nanoparticles during the Plasma Electrolytic Oxidation (PEO) process to improve the mechanical performance of the AZ31B Mg alloys. The surface morphology and composition were analyzed through the SEM and EDS mapping, which confirmed a denser, homogeneous coating. The Potentiodynamic Polarization characterization (PDP) in 3.5 wt.% NaCl solution showed that the corrosion current density of the bare Mg alloy reduces from 1.42×10 −7 A/cm 2 to 1.07×10 −10 A/cm 2 for the glass-addedPEO layer. The glass-filled PEO layer possesses a polarization resistance three orders of magnitude higher than that of the bare Mg substrate. Electrochemical Impedance Spectroscopy (EIS) analysis revealed a suppressed inductive response, near capacitive behavior, and higher impedance values (95–113 kΩ.cm 2 ) of the glass-filled PEO coating, ensuring the corrosion resistance of the glass-filled inner barrier layer and reducing the pitting corrosion. Meanwhile, the hardness of the bare sample increases from 58 HV to 245 HV for the glass-free PEO layer and further increases to 335 HV for the glass-incorporated PEO coating. The wear rate decreased to (0.49 ± 0.051) × 10 −4 mm 3 /Nm (two orders lower than the bare Mg substrate) and exhibited the lowest coefficient of friction. Thus, it can be inferred that incorporating nano-glass particles into the PEO layer is a promising approach for improving the corrosion and wear resistance of AZ31B magnesium alloy for the application of biodegradable implants.