Improved Corrosion Resistance of Microarc Oxidized Coatings on AZ31B Mg Alloy: Effect of Concentration of Sodium Lignosulfonate.

By combining microarc oxidation (MAO) technology in silicate electrolyte and introducing sodium lignosulfonate (SLS) as a functional additive, ceramic coatings were successfully prepared on the surface of AZ31B magnesium alloy, which significantly enhanced its durability and protective performance in corrosive environments. The study focuses on the effect of SLS concentration on the microstructure, chemical composition, and corrosion resistance behavior of the MAO coatings with help of SEM, XRD and electrochemical testing methods. SEM images showed that the MAO coating prepared in electrolyte containing 0.1 g/L SLS (MAO-0.1-SLS) exhibited the most smooth and dense structure. Electrochemical tests indicated that the MAO-0.1-SLS coating showing the best electrochemical properties in simulated body fluid. Its corrosion current density decreased to 9.33 × 10 A/cm, which is 3 orders of magnitude lower than the uncoated substrate. In summary, the incorporation of SLS as an additive significantly enhances the durability of MAO coatings applied to magnesium alloys, thereby offering a novel strategy for the utilization of magnesium alloys within the biomedical sector.