In vitro Degradation Studies on Mg-Zn-CeO2 Composites for Biodegradable Implant Applications

The development of magnesium (Mg) based biodegradable implants for temporary applications in biomedical engineering is a prospective research area. Recently, several new Mg alloys and composites were developed, and their efficacy as implant materials to manufacture temporary implants was assessed. Developing composites facilitates taking advantage of the diversified properties from the constituting phases in a single material. Hence, in the present study, cerium dioxide (CeO2) particles were added to Mg-1% Zn alloy with different fractions of the reinforcement through a stir casting route to experimentally investigate the in vitro degradation behavior in simulated environmental conditions. No impurities or formation of intermetallics were identified from the X-ray diffraction (XRD) studies and microstructural investigations. The presence of more CeO2 led to grain refinement (from 165 ± 12.3µm to 105 ± 7.1µm). The phases on the surface of the samples from the in vitro immersion study were assessed by XRD and scanning electron microscopy and observed that the composite with higher CeO2 has more mineral phases compared with the base alloy and the other composites. From the weight loss measurements, lower weight loss was observed for the composite with 2% CeO2. With the increased content of CeO2 up to 4%, the weight loss was marginally increased, which is attributed to the combined effect of increased galvanic corrosion and decreased degradation due to the deposited mineral phases. The results suggest the potential of adding CeO2 to Mg-1%Zn alloy to tailor the degradation for temporary implant applications.