Nano-hydroxyapatite/ZnO coating prepared on a biodegradable Mg–Zn–Ca bulk metallic glass by one-step hydrothermal method in acid situation

Mg68Zn28Ca4 BMG with 4 mm diameter was prepared by rapid solidification process. On the premise of guaranteeing the amorphous structure of the matrix, a dense nano-HA/ZnO coating with 16 mu m thickness and multilayer structure was prepared on the surface of BMG by a simple one-step hydrothermal method in acid situation. The microstructure, element distribution and corrosion resistance of HA/ZnO coated BMG were analyzed by XRD, SEM, EDS and electrochemical measurements. After hydrothermal treatment, nano-HA whisker with high crystallinity was grown on the surface of BMG. Comparing with pure Mg and BMG without coating, the corrosion resistance of BMG with HA/ZnO coating in SBF was greatly improved. Due to the presence of ZnO in the coating, the in vitro antibacterial rate of BMG is close to 100%. Hence, nano-HA/ZnO coated BMG exhibits good biocompatibility and outstanding corrosion resistance. As a temporary medical implant, nano-HA/ZnO coated BMG has prospective application.