Fabrication of chitosan/magnesium phosphate composite coating and the in vitro degradation properties of coated magnesium alloy

摘要

A composite coating was fabricated on home-developed Mg-Zn-Ca alloy to improve its biocorrosion resistance in simulated body fluid (SBF, Kokubo solution). The coating was prepared by micro arc oxidation (MAO) of the alloy, followed by dip-coating in chitosan solution. The coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The electrochemical performance of the MAO, chitosan and chitosan/MAO coated alloys was evaluated by anodic polarization measurements in SBF. After being coated by composite coating, anticorrosion performance was significantly enhanced, while single MAO or chitosan coating only improved anticorrosion properties within a limited range. The barrier effect and interface condition of composite coating were analyzed and related with the improvement in electrochemical performance. The present result indicates that fabrication of composite coatings is a significant strategy to slow down the degradation of Mg alloys, thus enhancing the potential of using Mg alloys as bio-implants.