Bidirectional properties of TiC, TiN and TiNC thin films deposited by radio frequency magnetron sputtering.

Abstract

Titanium nitride (TiN), titanium carbide (TiC) and titanium carbonitride (TiNC) thin films show promising practical applications due to their photoelectric properties and corrosion behaviour. In this work, we investigated the factors which may affect the optical properties and the corrosion behaviour of these coatings. The titanium coatings were carried out by sputtering using the target of Ti6Al4V (purity 99.96%) with different N2, CH4 and Ar partial pressures. XRD, FTIR, Raman and SEM with EDX studies show the formation of titanium nitride, titanium carbide coatings. Uv-vis spectroscopy was carried out to estimate the optical properties using the numerical Swanepoel method. Potentiodynamic polarization studies in Hank's solution show that the corrosion resistance is found to be in the order of C-TiN(2) > C-TiN(1) > TiN > TiC. A high protective efficiency was determined (60%) when comparing TiNC(2) and TiC corrosion current densities, which confirms the lower corrosion velocity and the higher passivation stability of the coatings composed with TiN and TiC phases. Electrochemical impedance spectroscopy studies show that the Rct increases in the following order: TiC < TiN < C-TiN(1) < C-TiN(2), highlighting the fact that C-TiN(2) coating has the higher corrosion resistance.