Micro-arc oxidation coating on porous magnesium foam and its potential biomedical applications

In this study, we fabricated a biodegradable porous metal using the AZ31 Mg alloy substrate with anodic coating for application in bioimplant scaffolds. The cellular Mg alloy was obtained by employing replication processes that use NaCl as a space holder under a controlled atmosphere. Further, vacuum pressure was applied for achieving the infiltration. The Mg porous samples were coated by a micro-arc oxidation (MAO) technique using a phosphate/calcium electrolyte. Further, the samples were examined by atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), compression tests and surface area measurements. The MAO technique allowed us to obtain a homogeneous coating layer of ~16.0 μm thickness with the surface across the foam structure comprising rounded pores with diameters of less than 3.0 μm. Ca, P, Mg and O are the main elements of the anodic coating. Furthermore, both the coated and uncoated porous samples exhibit similar values of approximately 1.5 GPa and 5.0 MPa for the Young's modulus and compressive strength, respectively.