Corrosion behavior of ZrN/Zr coated biomedical AZ91 magnesium alloy

Magnesium alloys are potential materials in biodegradable hard tissue implants. However, their fast degradation rates in a physiological environment constitute the main limitation for their applications. In this work, a ZrN/Zr bilayered coating is deposited on AZ91 magnesium alloy using a filtered cathodic arc deposition system. The ZrN/Zr bilayered structure buffers the serious mismatch between the substrate and ZrN coating thus improving film adhesion. The composition of the coating is evaluated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical behavior of the coated alloy is systematically studied by means of potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). Our results disclose that the corrosion resistance of the coated alloy is significantly improved.