The impact of mechanical post-treatment on the tribological and corrosion behavior of CrN/CrAlN coatings applied using the CAE-PVD technique

Abstract

This study examined how wet microblasting affects the tribological and electrochemical properties of CrN/CrAlN nanolayered coatings. The coatings were applied to 430 stainless steel substrates using cathodic arc evaporation (CAE), a physical vapor deposition (PVD) technique. The microblasting was performed at three different pressures (2, 4, and 6 bar) after the deposition process. Field emission SEM and X-ray diffraction techniques were employed to characterize the microstructure and morphology of the samples. The nanoscale indentation method was utilized to evaluate the indentation properties of the coatings. The tribological properties of the samples were investigated by means of a ball-on-disk tester. The coatings’ corrosion behavior was tested by EIS and PDP in a NaCl solution (3.5 wt.%). The wear results indicated that the friction coefficient decreased from 0.3 for the non-treated coating to 0.27, 0.23, and 0.5 for the coatings microblasted at 2, 4, and 6 bar, respectively. The wear resistance increased by 10 % and 23 % for the coatings microblasted at 2 and 4 bar due to the higher compressive residual stress and resistance against plastic deformation (H/E value). The EIS results revealed that the coating microblasted at 2 bar had the highest RP (2425 × 103 W cm2) and the lowest corrosion rate after 24 h of immersion in a 3.5 wt.% salt solution. The results showed that the corrosion resistance at 2 bar pressure improved approximately 16 times. The Potentiodynamic polarization (PDP) diagrams also showed that the coating microblasted at 2 bar had the lowest current density (6.3 nA cm2), indicating the highest corrosion resistance. Therefore, the optimal microblasting pressure for tribological and electrochemical applications was 4 and 2 bar, respectively.