Abstract
A double layer coating (Ca-P/PEO) was designed to form on pure magnesium. The Ca-P coatings were prepared at three pH values of the solution. The morphology, phase composition, microstructure, corrosion resistance, and degradation properties of the samples were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and in vitro assessments. The XRD results indicate that the 5.7Ca-P coating is mainly composed of octacalcium phosphate (OCP). The potentiodynamic polarization test indicates that the corrosion current density of the 5.7Ca-P/PEO coated Mg is 100 times and 3 times lower than that of uncoated Mg before and after immersion in SBF solution for 168 h, respectively. The 5.7Ca-P coating promotes the nucleation of osteoconductive minerals (i.e., bone-like apatite), and the hydro-xyapatite (HA) layer formed on the surface of the 5.7Ca-P coating is dense, thick, and stable after immersion in SBF solution for 30 days. These experimental results have demonstrated that the 5.7Ca-P/PEO coating can introduce a high biocompatibility of the bone-Mg substrate interface and provide long-term stable protection in SBF solution in the initial degradation stage.
NSTL
Elsevier