Effect of surface treatment on the bioactivity and electrochemical behavior of magnesium alloys in simulated body fluid

The effect of surface treatment using NaOH or H₂O₂ on the bioactivity and corrosion behavior of AZX310, AZ91D, AM50, and AZ31 Mg alloys in simulated body fluid (SBF) has been studied with the aid of surface morphological assessment, in vitro characterization, and electrochemical measurements. The influence of immersion time on the behavior of the treated alloys in SBF was also investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed successful surface modification upon treatment of alloy surface with NaOH and H₂O₂. XRD and SEM analyses also revealed that surface modification enhances formation and growth of hydroxyapatite (HA). Formation of HA layer on the alloy surface was further confirmed by Fourier transform infrared spectroscopy analysis. In vitro immersion test reveals that pH of SBF solution containing treated alloys is lower than that containing untreated alloy. However, pH increases with immersion time. Results from weight loss and electrochemical measurements indicate that treated alloys possess higher corrosion resistance in SBF than the untreated ones. H₂O₂ treated alloys demonstrated greater corrosion resistance in SBF than NaOH treated alloys.