Effect of Ca content on biomineralization of Mg-Ca alloys

Abstract

The mechanical and physical properties of biodegradable Mg-based alloys make them suitable for temporary orthopaedic implants. However, processing them in such a way that it degrades at the required rate in physiological environment is a challenge. Among the possible methods, in situ formation of calcium phosphate (CaP) during service to control the degradation rate is least explored. The CaP formation can be improved by enhancing the biomineralization of Mg alloys. The present work investigates the effect of Ca concentration (0, 0.5, 1, and 2 wt.%) on the biomineralization of Mg-Ca alloys. Optical microscopy observations and X-ray diffraction analysis showed that Mg-xCa (x = 0.5, 1 & 2 wt. %) alloys were composed of two phases, α-Mg and Mg2Ca. The electrochemical corrosion test in biomimetic NaCl solution and immersion test in simulated body fluid shows that the corrosion rate increases as Ca content increases. The studies reveal that a low calcium content single-phase microstructure is preferred over a multiphase morphology for promoting biomineralization.