Nano indentation measurements on nitrogen incorporated diamond-like carbon coatings

Nanoindentation testing was performed on nitrogen (N-2) incorporated diamond-like carbon (N-DLC) films and deposited using radio-frequency plasma-enhanced chemical vapor deposition technique, with varied percentage of nitrogen partial pressures of 0, 44.4, 66.6, and 76.1%. The values of nanohardness (H) and elastic modulus (E) of these films were obtained from 38 to 22 GPa and 462 to 330 GPa, respectively, as the partial pressure of N-2 increases from 0 to 76.1%. Further, these films were studied for % elastic recovery, ratio between residual displacement after load removal and displacement at maximum load (d (res)/d (max) ), plastic deformation energy and plasticity index parameter (H/E). Both hardness per unit stress and plasticity index per unit stress were found to be maximum at N-2 partial pressure of 76.1%. X-ray photoelectron spectroscopy measurements confirmed the presence of N-2 in these films.