Effect of ZnO pore-sealing layer on anti-corrosion and in-vitro bioactivity behavior of plasma electrolytic oxidized AZ91 magnesium alloy

A pore-sealing layer consists of ZnO nanoparticles was successfully prepared on plasma electrolytic oxidized AZ91 magnesium alloy using electrophoretic deposition method to improve its biomedical features. Investigating the anti-corrosion performance of duplex coating in simulated body fluid revealed that the sealing of surface inherent defects leads to a decrease of ~150 times in corrosion current density and an increase of ~50 times in impedance module, which indicates the difficulty of penetration pathways caused by layer thickness, surface porosity and roughness. Additionally, the ZnO nanoparticles embedded in duplex coating porosity considerably improved in-vitro bioactivity, resulting from their catalytic activity and high preferred nucleation sites for precipitating calcium phosphate compounds.