Corrosion degradation of Mg1Ca1Si alloy in Ringer solution

Mg alloys exhibit attractive mechanical properties, low density and high strength-to-weight ratio.
Therefore they are widely used as structural materials in the automotive and aerospace sectors. In
recent years, Mg alloys are considered as a new class of biodegradable implant materials. It has been
revealed that magnesium alloys exhibit very good biocompatibility and their density is close to that of
natural bones (1.8 - 2.1 g cm 3 ). In vitro and in vivo studies have shown that magnesium alloys easily
undergo resorption and do not cause allergic reactions. Magnesium alloys exhibit very low corrosion
resistance in physiological solutions.
The corrosion mechanism of Mg1Ca1Si magnesium alloys in the Ringer solution was investigated by
means of electrochemical techniques like: Linear Sweep Voltamperommetry (LSV), Electrochemical
Impedance Spectroscopy (EIS), chronoamperometry were performed. All electrochemical
measurements have been performed in the Ringer solution at 37C and pH = 7.2. The surface analysis
after corrosion tests were performed by using FE-SEM. Moreover, the chemical analysis of the solution
after corrosion tests was performed by ICP-MS and UV-vis spectroscopy.
It has been revealed that the corrosion of Mg1Ca1Si alloys starts at the interface matrix / precipitates
and the eutectic (mixture of  and Mg 2 Ca phases) is a week place where the corrosion starts. After
corrosion tests the magnesium and calcium species were detected in the solution. In order to improve
the corrosion resistance the chitosan coatings were deposited on the surface of Mg1Ca1Si alloy. The
electrochemical tests have been shown that such coatings enhance the corrosion resistance of Mg alloy
in the Ringer solution.
Acknowledgements
The authors would like to thanks to European Commission for financial support in the frame of project H2020-
MSCA-ITN-2017, grant agreement no. 764977 -mCBEEs