Comparing electrochemical behavior of applied CrN/TiN nanoscale multilayer and TiN single-layer coatings deposited by CAE-PVD method

The main goal of this study is to compare the electrochemical behavior of CrN/TiN multilayer coating and TiN single-layer coating applied by cathodic arc evaporation (CAE) -physical vapor deposition (PVD) on the substrate of Ti-6Al-4 V in Hank's solution. So, a TiN single-layer coating was formed using PVD method as well as CrN/TiN multilayer coating under totally the same conditions including deposition temperature, working pressure, bias voltage, cathode current and deposition time. To identify the phases in the coatings, X-ray diffraction (XRD) was utilized in order and field emission scanning electron microscopy (FE-SEM) was used in order to study the microstructure of coating. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) tests were also carried out for corrosion measurements. In the corrosion evaluation, the PDP and EIS tests were performed for the samples after immersion in Hank's solution for 24 hours to reach the steady state. The obtained results from PDP curves showed that the specimen with CrN/TiN multilayer coating exhibited better corrosion behavior than the TiN single-layer coatings. This improvement in corrosion resistance is probably due to the high density of the layers in the CrN/TiN multilayer coating that prevents the penetration of the corrosive solution to the substrate.