Corrosion behavior of bioresorbable Ca-Mg-Zn bulk metallic glasses

Abstract

In this work, bulk metallic glasses Ca60Mg20Zn20 (BMGs) in the form of plates were successfully prepared by the high-pressure die casting. The glassy alloy with the biocompatible elements Ca, Mg and Zn was produced as bioresorbable material for potential biomedical applications. The structure of bulk amorphous samples was confirmed by a conventional X-ray diffraction and a differential scanning calorimetry (DSC) method. The corrosion behavior of the glassy samples was studied by electrochemical measurements and immersion tests in a physiological and Ringer's solution. The results of immersion show that the volume of H2 evolved after 480min in Ringer's solution (24.9ml/cm2) is higher in comparison with the measurements conducted in a physiological fluid (13.1ml/cm2). The open-circuit potential (EOCP) for the Ca60Mg20Zn20 glassy sample after 60min of incubation in Ringer's solution and a physiological fluid was found to be −1543 and −1566mV vs. a saturated calomel electrode (SCE). The electrochemical measurements indicated a shift of the corrosion potential (Ecorr) from −1551mV for sample tested in a physiological fluid to −1527mV for specimen immersed in Ringer's solution. In order to further understand the corrosion behavior of the studied material the X-ray photoelectron spectroscopy (XPS) measurements were used to determine the elemental composition of the corrosion products after polarization. The corrosion products were identified to be CaCO3, Mg(OH)2, CaO, MgO and ZnO. The uniform corrosion mechanism is considered. The energy-dispersive X-ray spectroscopy (EDS) results suggest that calcium and magnesium hydroxides and calcium oxides were mainly formed on the surface of studied alloy. The post-experiment analyses of surface morphology were conducted by a scanning electron microscopy.