Structural and mechanical characterisation of the chromium nitride hard coating deposited on the silicon and glass substrate

Abstract

Chromium Nitride (CrN) thin films are known for their comparatively good mechanical properties. CrN was deposited on Silicon (100) and glass substrates by using DC magnetron sputtering and the influence of the partial nitrogen content and different gaseous environment on their microstructural characteristics were investigated in the present work. The CrN films were characterised with X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Atomic Force Microscopy (AFM) and Nanoindentation was used to characterise the structural and mechanical properties of the deposited thin film. The filmsshowed the [200] preferred orientation at lower (at 20%) nitrogen contents while the intensity of the peak [111] increases with the increase in the nitrogen content. The Cr2N (220) peak was identified at a nitrogen content above 30%, but for nitrogen content above 40%, the CrN phase was observed in both films deposited on Si(100) and glass substrates. The preferred orientations of the CrN thin films are strongly influenced by the nitrogen content inside the chamber as observed in the present work. The surface roughness and deposition rate were observed in a reducing trend with the increasing N2 content and temperature from 20.31 to 2.71nm and from 30.16 nm/min to 25.66nm/min, respectively. The hardness and modulus of pure N2 films deposited on the Si substrates were evaluated by nanoindentaion testing and indicated 31 GPa and 250 GPa, respectively.