Corrosion resistance of transition metal nitride films deposited on AISI M2 steel

Abstract

In this work the corrosion behavior of zirconium nitride (ZrN), titanium nitride (TiN), chromium nitride (CrN), niobium nitride (NbN) and tantalum nitride (TaN) films deposited on commercial AISI M2 steel using unbalanced magnetron system (UBM) was investigated. The corrosion resistance was evaluated by testing electrochemical impedance spectroscopy (EIS) on a 3% solution of NaCl, changing the test time from 1 h to 7 d. The higher resistance to corrosion was obtained for NbN and ZrN films when these materials were deposited in the lower unbalanced configuration of UBM system. The coatings show degradation with the immersion time due to the microstructure defects, which become diffusion channels so that the corrosive solution can react with the substrate surface. Corrosion mechanisms in the coatings produced are discussed in this research.