Low friction and protective diamond-like carbon coatings deposited by asymmetric bipolar pulsed plasma

Diamond-like carbon (DLC) thin films have been prepared at room temperature by plasma-enhanced chemical vapour deposition (PECVD) using pulsed-DC power and CH4 as precursor. Tribological tests of these DLC films have been carried out with a nanotribometer and a calotest instrument adapted for wear measurements. Friction coefficients ranged from 0.15 to 0.20, which differ from values obtained by other techniques. In this study we have systematically measured the abrasive wear rate and friction coefficient of DLC films deposited at different conditions (pulse frequency and peak voltage), and we have discussed the results in terms of DLC structure and surface morphology. These films could find application as ultrathin anti-friction and anti-wear protective coatings, hydrophobic coatings, gas diffusion barriers and dielectric layers in electronic devices.