Improved Corrosion Resistance of Cathodic Arc Evaporated Al0.7Cr0.3-xVxN Coatings in NaCl-rich Media
The corrosion resistance of cathodic arc evaporated Al0.7Cr0.3-xVxN coatings with a vanadium content up to 22.3 at.% has been electrochemically tested in a 0.1 M NaCl-solution. Significant improvement in the open porosity and corrosion rate was observed for coatings with higher V-contents, due to a denser and more refined coating morphology. Further reduction in the open porosity rate was achieved through an annealing step in air at 700 °C. Here, the formation of an AlVO4 top-oxide and underlying oxygen-rich V-depletion zone provides additional sealing of the coating surface, whilst reducing the corrosion current density to a final 1.59×10-9 A/cm2.
O.E. Hudak, P. Kutrowatz, T. Wojcik, E. Ntemou, D. Primetzhofer, L. Shang, J. Ramm, O. Hunold, S. Kolozsvári, P. Polcik, H. Riedl