Structural and mechanical properties of nanolayered TiAlN/CrN coatings synthesized by a cathodic arc deposition process

Multilayered TiAlN/CrN as well as monolayered CrN and TiAlN coatings were synthesized by cathodic arc evaporation with plasma enhanced duct equipment, using Cr and Ti50Al50 alloy cathodes. Optical emission spectra including atomic and ionized Ti, atomic Al and Cr, excited and ionized nitrogen (N2, N2+, and N22+) revealed that excitation, ionization and charge transfer reactions of the Ti–Al–N and Cr–N plasma occurred during the multilayered TiAlN/CrN coating process. The preferred orientation was changed from (200) in CrN and TiAlN monolayered coatings to (111) plane in the multilayered TiAlN/CrN coatings. The multilayered TiAlN/CrN films had smaller crystallite size than the monolayered CrN and TiAlN films. The multilayered TiAlN/CrN coating with periodic thickness of 18 nm exhibited the highest H3/E*2 ratio value of 0.193 GPa, indicating the best resistance to plastic deformation, among the studied CrN, TiAlN and multilayered TiAlN/CrN coatings. The multilayered TiAlN/CrN coatings also showed the best adhesion strength during scratch tests. It has been found that the structural and mechanical properties of the films were correlated with the multiple cathode design and nanolayer thickness.