Effect of bilayer period on CrN/Cu nanoscale multilayer thin films

Thin films with a CrN/Cu multilayer structure comprising a superhard coating with a lamination of hard transition metal nitride and soft metal were synthesized by Closed Field Unbalanced Magnetron Sputtering (CFUBMS). The bilayer thickness (λ) of all of the laminated layers was controlled via the rotational speed of the substrate holder within the range from 4.7 to 47.1 nm. The structural characterization of the coatings was investigated using high resolution X-ray diffraction (HRXRD) and field emission transmission electron microscopy (FETEM). The preferred orientation of the CrN/Cu nanoscale multilayer thin films was CrN (200) and Cu (200). The surface morphology of the films was examined by atomic force microscopy (AFM). The mechanical properties of the coatings, as determined by nano-indentation testing and the ball-on-disc test varied with the bilayer thickness (λ). The multilayer with a bilayer thickness of 7.9 nm exhibited high hardness, high resistance to plastic deformation, and high wear resistance.