Corrosion resistance and in vitro bioactivity of Si-containing coating prepared on a biodegradable Mg-Zn-Ca bulk metallic glass by micro-arc oxidation

A Mg-Zn-Ca bulk metallic glass (BMG) with a critical casting size of 5 mm was successfully developed. A porous and rough silicon-containing coating was achieved on the BMG by micro-arc oxidation (MAO) technique. The degradability and bioactivity of the coatings were analyzed by immersion tests in the stimulated body fluid (SBF). The results indicated that the corrosion resistance of the BMG specimens was significantly improved after MAO treatment. The spontaneous formation of carbonated hydroxyapatite (HA) on the porous layer demonstrated that the prepared MAO coating has a high bioactivity as a result of its phase composition and porous surface structure. The present work may provide a promising way for surface modification of Mg-based BMGs through fabrication of MAO coatings with good corrosion resistance and high bioactivity.