Corrosion behavior of TiN, TiAlN, TiAlSiN thin films deposited on tool steel in the 3.5 wt.% NaCl solution

TiN, TiAlN and TiAlSiN hard coatings were deposited onto AISI H13 tool steel by cathodic arc plasma method. X-ray diffraction (XRD) analysis confirmed that incorporation of Al and Si into TiN led to refinement of microstructure. From the results of potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) test conducted in an aerated 3.5% NaCl solution, the TiAlSiN film showed the best corrosion resistance with the lowest corrosion current density and porosity, the highest protective efficiency and total resistance (pore resistance plus charge transfer resistance).