Tribocorrosion behaviors of a biodegradable Mg65Zn30Ca5 bulk metallic glass for potential biomedical implant applications

In this study, the tribological behavior of Mg65Zn30Ca5 BMG under dry friction in air and lubrication friction in phosphate buffered saline (PBS) solution were investigated using ball-on-disk reciprocating sliding. The results were compared with those of AZ31B alloy and pure Mg. The Mg65Zn30Ca5 BMG exhibits the highest dry wear resistance among three Mg-based alloys. Nevertheless, under lubricated sliding in PBS solution, the wear rate of Mg65Zn30Ca5 BMG and pure Mg increases whereas that of AZ31B decreases in comparison with the cases under dry friction. The electrochemical results suggest that the corrosion resistance of Mg-based alloys in PBS solution decreases in the following consequence: AZ31B, Mg65Zn30Ca5 and pure Mg, which results in an accelerated wear rate of Mg65Zn30Ca5 and pure Mg during sliding in PBS solution. The tribocorrosion results demonstrate that the tribological contact decreases the corrosion potentials and increases the corrosion current densities of Mg-based alloys. The tribocorrosion of Mg-based alloys is dominated by their corrosion current density. The possible mechanism of synergistic effects of corrosion and wear deterioration is discussed. The present study provides the hints for the design of wear-resistant Mg-based BMGs for further orthopedic applications. (C) 2018 Elsevier B.V. All rights reserved.