Nanocomposite Coatings and Electrochemical Corrosion Behavior of TZAV-30 Titanium Alloy in Simulated Body Fluid Solution

The ultra-low elastic modulus (~34 GPa), high strength, and low density of Ti-Zr-Al-V series alloys show a great application potential as implant materials. However, their surface properties need to be studied and improved before clinical applications. In this work, nanocomposite coatings are deposited on the surface of the Ti-30Zr-5Al-3V alloy through the magnetron sputtering technique at various N2 flow rates. X-ray diffractometer, scanning electron microscope, and electrochemical workstation are employed to investigate the effect of the N2 flow rate (NFR) on the phase constitution, microstructure, and corrosion resistance in a simulated body fluid of the nanocomposite coatings. The phase constitution of the nanocomposite coating changes from α-Ti + Ti2N to α-Ti (inner layer) + Ti2N + TiN (outer layer) as the NFR increases from 6 × 10-5 to 4.8 × 10-4 m3/h. The tiny nanograins (~30 nm) cluster together and then coarsen into lumpy grains of an average size of 117.2 nm with the increase of the NFR. Analyses of potentiodynamic polarization curve and electrochemical impedance spectroscopy prove the obvious enhanced corrosion resistance of specimens with the nanocomposite coating. And the specimen, after deposition at the NFR = 2.4 × 10-4 m3/h, has the best corrosion resistance. The formation of TiN and the cluster of tiny nanograins are the major reasons for affecting the corrosion resistance of the nanocomposite coating.