Electrochemical Characterization of Ti5Si3/TiC Nanocomposite Coating in HCl Solution

A novel Ti5Si3/TiC nanocomposite coating was successfully engineered onto Ti-6Al-4V alloy substrate by double glow discharge plasma technique. The microstructure of the newly developed nanocomposite coating was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the nanocomposite coating exhibits cauliflower-like structure composed of Ti5Si3 grains with an average grain size of similar to 15 nm and irregular TiC nanoparticles located at the boundaries of cauliflower-like architecture. The electrochemical behavior of the nanocomposite coating and the reference materials (i.e., monolithic Ti5Si3 coating and uncoated Ti-6Al-4V alloy) was evaluated in 5 wt.% HCl solution by a variety of electrochemical techniques, including open circuit potential measurement, potentiodynamic polarization, electrochemical impedance spectroscopy and Mott-Schottky analysis. The results revealed that the corrosion resistance of the Ti5Si3/TiC nanocomposite coating is slightly lower than that of the monolithic Ti5Si3 nanocrystalline coating, but obviously higher than that of uncoated Ti-6Al-4V in 5 wt.% HCl solution.