Improving corrosion resistance of Ti–6Al–4V alloy through plasma-assisted PVD deposited nitride coatings

• Coated alloy increased corrosion resistance of the uncoated alloy.
• The coated alloy behaved passively, the uncoated alloy behaved actively.
• TiN coated alloy presented the highest corrosion resistance at 25 °C.
• The corrosion rate increased with increasing temperature.
• TiAlN/TiAlCrN coating suffered spallation in all experimental temperatures.

TiN and TiAlN/TiAlCrN were deposited on the alloy Ti–6Al–4V by means of plasma-assisted PVD technique in order to improve its corrosion resistance in a 2 M HCl solution at 25, 60, and 80 °C. The corrosion behaviour was investigated using open-circuit potential vs. time measurements, potentiodynamic polarization and electrochemical impedance spectroscopy. The uncoated Ti–6Al–4V alloy demonstrated an active behaviour with an active–passive transition in the HCl solution. The TiN and TiAlN/TiAlCrN coated Ti–6Al–4V alloy presented a passive behaviour. The corrosion resistance of the coated alloy was superior, which was evidenced by lower corrosion current densities and higher impedance values.