Corrosion study of Mg-Ca and Mg-Zn biomedical alloys in the Hank's solution

In recent years, much attention has been devoted to the study of corrosion of magnesium alloys, which
can be used as implants. Magnesium alloys exhibit good biocompatibility and the density close to that of
natural bones (1.8 - 2.1 g cm 3 ). The corrosion resistance of Mg alloys depend on their chemical
composition and casting technology.
In this work, the corrosion rate of Mg1Ca and Mg20Zn alloys in the Hank’s solution was investigated. In
order to study the corrosion degradation of Mg alloys the following electrochemical techniques were
used: Linear Sweep Voltamperommetry (LSV), Electrochemical Impedance Spectroscopy (EIS),
chronoamperometry. The corrosion test were performed in the Hank’s solution at 37C and pH = 7.2.
The microstructure of both alloys has been investigated by means of XRD and FE-SEM/EDS
measurements. Surface analysis techniques like XPS and FT-IR were used to study the chemical
composition corrosion products. To slow down the corrosion of Mg alloys, the chitosan coatings were
deposited on the surface of MgCa and MgZn alloys.
Magnesium alloys undergo the active corrosion in the Hank’s solution. In the case of Mg1Ca alloy, the
corrosion starts at the grain boundaries where Mg 2 Ca precipitates are located. In the case of Mg20Zn
alloy, the matrix -Mg is more prone to corrosion than the precipitate MgZn 2 . The Mg20Zn exhibits
higher corrosion resistance than Mg1Ca alloy in the Hank’s solution. The chitosan coatings deposited on
the surface of both Mg alloys significantly reduce their corrosion rate. Chitosan layer is adsorbed at the
surface of Mg alloys and blocked their anodic dissolution. The structure of the chitosan coatings have
been studied by FT-IR spectroscopy.
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.