Nanotribology of pulsed direct current magnetron sputtered diamond like carbon films

The presented research for the first time establishes the relations among nanotribological features, structural properties and deposition parameters (acetylene flow and bias voltage) of diamond like carbon films deposited by pulsed direct current magnetron sputtering. The nanotribological behaviour of hydrogen free and hydrogenated diamond-like carbon films (a-C:H) deposited by pulsed direct current magnetron sputtering was investigated using atomic force microscopy (AFM). A structural analysis with Raman spectroscopy showed that elevated acetylene concentrations in the process gas atmosphere favoured a decreased structural disorder in the a-C:H matrix, which was derived from the decreasing full with at half maximum of the G-band in the spectrum from 191 ± 3 cm− 1 to 173 ± 1 cm− 1. More ordered films showed friction coefficients of ~ 0.001, while having still relatively high hardness. Spectroscopic data could be associated with mechanical properties: higher structural disordering of the films showed highest hardness (23.3 ± 0.3 GPa). Coatings deposited only with argon as sputtering gas have low friction coefficients ~ 0.002 and low wear rates ~ 1.2 nm. In general, the deposited films were found to be relatively free of defects and smooth, which was derived of an averaged roughness of the film surfaces of less than 1 nm.