Structure, Mechanical and Tribological Properties of Me-Doped Diamond-Like Carbon (DLC) (Me = Al, Ti, or Nb) Hydrogenated Amorphous Carbon Coatings

Abstract

Metal containing hydrogenated diamond-like carbon coatings (Me-DLC, Me = Al, Ti, or Nb) of 3 ± 0.2 μm thickness were deposited by a magnetron sputtering-RFPECVD hybrid process in an Ar/H2/C2H2 mixture. The composition and structure were investigated by Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The residual stress was measured using the curvature method and nanoindentation was used to determine the hardness and the Young’s modulus. A Ball-on-disk tribometer was employed to investigate the frictional properties and sliding wear resistance of films. The results show that the properties depend on the nature and the Me content in the coatings. The doping of the DLC coatings leads to a decrease in hardness, Young’s modulus, and residual stresses. Wear rate of the films first decreases with intermediate Me contents and then increases for higher Me contents. Significant improvements in the friction coefficient on steel as well as in the wear rate are observed for all Al-DLC coatings, and, concerning the friction coefficient, the lowest value is measured at 0.04 as compared to 0.07 for the undoped DLC.