Mechanical characteristics of an anodized magnesium alloy for biodegradable implants

In recent years, magnesium (Mg) alloys have emerged as possible biodegradable implant materials; however the degradation rate of Mg occurs at a higher rate than tolerable for the human body. Plasma electrolytic oxidation (PEO) has been used in the past as a useful surface treatment technique to improve the anti-corrosion properties of Mg alloys by forming protective coatings. This present work focuses on the effect of electrolyte solution on the corrosion, microstructural, and nanomechanical behavior of PEO coatings for possible use in biodegradable implants. The experimental parameters applied during PEO process did influence the structure, thickness, and morphology of the coating. Microstructural characterization of the coating was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) followed by image analysis and energy dispersive spectroscopy (EDX). Further, nanoindentation was employed to evaluate nanohardness and Young's modulus of the PEO coating. The results show beneficial effects of the PEO coating to enhance the corrosion resistance of the uncoated AZ31 magnesium alloy. The XRD pattern shows that the components of the film vary based on electrolyte solution. The film composition does affect the nanomechanical behavior.