Corrosion behaviour of facile coated ZnO on Mg–Zn–Zr alloy in Ringer's physiological solution

Abstract

Magnesium alloys have received increasing consideration as biodegradable implants owing to their high specific strength, excellent biocompatibility and non-toxicity but their biomedical applications are limited due to low corrosion resistance which can be improved by surface modification and alloying with suitable elements. Various surface modifications of Mg alloys by deposition of different coatings are used to prevent untimely dissolution. This study presents the corrosion behaviour of a thin ZnO coating deposited on a Mg–Zn–Zr alloy by electrophoretic deposition in the Ringer's solution at 37°C. It was found that the ZnO coating is compact, homogeneous and significantly enhanced its corrosion resistance according to electrochemical test. The polarisation test showed a two orders of magnitude lower current density than that of the bare alloy, while EIS study found a two orders of magnitude greater ZnO coating impedance increasing in bioactivity. The bare specimens showed the development of cracks on the surface whereas the ZnO coated alloy showed no signs of pitting.