A comparative study of the electrochemical corrosion behavior between Cr2N and CrN coatings

Abstract

Thick Cr2N and CrN coatings were successfully prepared by arc ion plating (AIP) at a high deposition rate of more than 15 μm/h. The electrochemical corrosion behavior of Cr2N and CrN coatings in 3.5 wt% NaCl solution was investigated comparatively using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the corrosion current (Icorr) of Cr2N coating was only 0.85 nA cm−2, which was lower than that of CrN coating of 5.5 nA cm−2. And its charge transfer resistance (Rct) of ∼7.19 × 106 Ω cm2 increased by about two orders of magnitude compared to that of CrN coating, indicating that Cr2N coating has better corrosion resistance. Additionally, the nitride coatings showed different surface morphologies after corrosion tests, where the relatively slight corroded surface of Cr2N coating may be related to its larger range of passive region and higher pitting potential (Epit).

Keywords

• Cr2N coating
• CrN coating
• electrochemical corrosion
• arc ion plating