Effect of Bias Voltage on Corrosion Behavior of Nanostructured TiN Coatings Deposited on Ti-6Al-4V Alloy by CAE-PVD Technique

In this study, TiN coatings were deposited on Ti-6Al-4V alloy surface using cathodic arc evaporation (CAE) deposition process at three different bias voltages (-150, -200 and -250 V) applied to the substrate. In this regard, the effect of bias voltage on the microstructure and corrosion behaviour of coatings was studied. The microstructure of the coated specimens was analysed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and atomic force microscopy (AFM). The corrosion behaviour of the coatings was studied by potentiodynamic polarization (PDP) experiments and electrochemical impedance spectroscopy (EIS) in the simulated media. Studies on SEM images showed that formed coatings at bias of -200 V exhibited the least amount of needle like cavities (0.4%) and macroparticles. Studying the effect of bias voltage on the corrosion behaviour of the coatings deposited at three bias voltages showed that the maximum corrosion resistance was obtained at -200 V and this voltage had the least current density in polarization measurements (5.59x 10(-7) A/cm(2)). So, it was considered as the optimal bias voltage.