Improved corrosion protective performance of chitosan coatings reinforced with nano-ZnO on degradable magnesium alloy in simulated body fluid

The chitosan (CTS) coatings have been widely studied as a biocompatible coating on biodegradable magnesium (Mg) alloys to improve the corrosion resistance and antibacterial performance for clinical application. However, the high porosity of CTS coatings cannot achieve the ideal long-time corrosion resistance in human physiological environment. In this work, a nano-ZnO/CTS coating was employed to Mg alloy substrates by the dip-coating method. The surface characteristics of samples were examined by FTIR, XRD, SEM–EDS and contact angle measurements. The particle size and suitable dispersion of nano-ZnO were confirmed by TEM. Further, the corrosion protection behavior of the coatings was examined in simulated body fluid using potentiodynamic polarization, EIS and SECM analysis. AFM was applied to determine the surface morphologies of the samples after the polarization test. The corrosion experimental results showed that the CTS coating modified by nano-ZnO particles exhibited enhanced corrosion protection ability and reduced the roughness of the corroded surface by 68.8%.