Effect of carbon doping on electrochemical behaviour of nanocrystalline Ti5Si3 film in NaCl solution

The nanocrystalline Ti5Si3 and Ti5Si3C0.8 films with an average grain size of 15 nm were prepared on Ti–6Al–4V alloy substrate by double glow discharge plasma technique. The electrochemical behaviour of two nanocrystalline films has been characterised by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution. The electronic properties of the passive films were investigated by Mott–Schottky analysis. The results revealed that the calculated donor densities are lower and the space charge region thicker for nanocrystalline Ti5Si3C0.8 film as compared to nanocrystalline Ti5Si3 film, suggesting that the passive layer formed is more protective.