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.

Niobium-Containing DLC Coatings on Various Substrates for Strain Gauges

“…On Kapton HN foils the elevated gauge factors as a result of crack formation were detected at Nb contents of 50-70 at %, which correlates with the increased film stress and the morphology change. Other investigations at lower Nb-contents (Me/C-ratio up to 0.2) showed stress values around −2 GPa for pure DLC-films, decreasing to values as low as −0.02 GPa with Nb embedded in the DLC accompanied with a decreasing hardness [4,5]. Compared to these values the stress in the coatings of the present study is relatively low.…”

“…Compared to these values the stress in the coatings of the present study is relatively low. Reason for the decrease of stress with increasing metal ratio is the decreasing content of C sp 3 and relaxation of distorted bonds induced by the metal [4].…”

“…This type of "metal-doped" material is often referred to as a-C:H:Me or Me-DLC in the literature. The addition of metal to DLC has several effects on the material properties: it reduces the internal stress due to a promotion of the graphite phase and disorder in the DLC matrix at low metal ratios [4,5], it can increase the electrical conductivity over 15 orders of magnitude [6], and for Ni and Pd, it was possible to develop piezoresistive materials of high strain sensitivity combined with a low TCR [7][8][9]. Our earlier investigations of a-C:H:Nb stated its great potential for strain sensors with a gauge factor of 35.5 and an TCR near zero [10].…”

The Influence of Plasma-Assisted Production and Milling Processes of DLC Flakes on Their Size, Composition and Chemical Structure

“…This, however, does not change the fact that this area is still valid and numerous researchers continue their studies on other forms of carbon, including diamond-like carbon (DLC). DLC is excellent as a low-friction or anti-wear coating [8,9] especially in medical applications [10,11] and it is often modified by adding various elements, e.g., Si, Ag, F or Ti [12][13][14]. It can also be used for the production of carbon-based fragmented materials, which are usually described in the literature as flakes or powders [15,16].…”

Lubricating Properties of Cyano-Based Ionic Liquids against Tetrahedral Amorphous Carbon Film

“…These polymer brushes exhibit an ultra-low friction coefficient of less than 0.01 [27,28]. Diamond-like carbon (DLC) is also used as one of the effective friction materials for reducing friction between surfaces [29,30]. Lubricating properties of cyano-based ionic liquids in steel/DLC and DLC/DLC contacts have been evaluated, and these combinations have been reported to exhibit low friction [17,20,[31][32][33].…”