Tribological and mechanical behaviors of CrN/a-CNx superlattice thin films

CrN/a-CNx superlattice thin films, which consisted of a superhard coating combined with a lamination of a hard transition metal nitride and lubrication material, were synthesized by Closed Field Unbalanced Magnetron Sputtering (CFUBMS). The bilayer period (λ) was controlled in the range from 3.1 to 37.7 nm via the rotational speed of the substrate holder. The preferred orientation of the CrN/a-CNx superlattice thin films was CrN (200). Nano-indentation testing showed that the hardness of the coatings varied from 20 to 32 GPa as the bilayer period (λ) was varied from 3.1 to 37.7 nm with the highest hardness being obtained with a bilayer period of about 6.3 nm. In this case, the lowest friction coefficient was also obtained, due to high plastic deformation resistance.