Hydrothermal Coating of the Biodegradable Mg-2Ag Alloy

Developing antibacterial biodegradable Mg alloys is of paramount importance to prevent infection and inflammation during the healing process. In this regard, the Mg-2Ag alloy is proposed as a suitable candidate with appropriate biocompatibility as well as antibacterial activity. However, its rapid degradation rate limits its clinical application. To tackle this problem, the hydrothermal coating technique was employed to synthesize a barrier coating to enhance the degradability of the Mg-2Ag alloy using distilled water as the reagent. Field emission scanning electron microscopy (FESEM) micrographs and X-ray diffraction (XRD) patterns showed that a hydroxide coating was formed on the studied samples. Furthermore, it was observed that the substrate microstructure plays an essential role in the obtained coating quality and hence, the degradation behavior. The dendritic microstructure with the nonuniform distribution of Ag-rich precipitates of the as-cast Mg-2Ag alloy lead to undesirable cracks and holes in the coating owing to Mg deficiency to form Mg(OH)2, whereas the solution-treated alloy with a homogenized microstructure resulted in the formation of a more compact, thick, and integrated coating, which remarkably improved the corrosion resistance of the alloy.