The mechanical properties of energetically deposited non-crystalline carbon thin films

Abstract

The mechanical behaviour of carbon films prepared with a variety of densities and microstructures was investigated using nanoindentation. Deposition energies between 25 and 600 eV and temperatures in the range 25-600˚C were used. Films prepared at low temperatures and moderate energies were amorphous with a high density. Finite element methods were used to model the stress fields, reproduce the indentation behaviour and evaluate elastic properties. Young's moduli up to 670 GPa and a low Poisson's ratio of ~ 0.17 were found, comparable to polycrystalline cubic boron nitride, one of the hardest materials known. Films with the same density did not always show the same behaviour, emphasising the role of microstructure in determining mechanical response. Extended graphite-like regions within the films grown at high energy and high temperature, observed in transmission electron microscopy caused plastic deformation and failure to recover after a complete

Micro-tribological performance of fullerene-like carbon and carbon-nitride surfaces

“…The cyclical phenomenon is controlled principally by a tribomechanical process due to plasticity events induced by localized shear as discussed in ref [17], but in our case, the good mechanical properties of the FL structure (hardness above 16 GPa and elastic recovery higher than 90%) allows an anelastic behavior [46] of the bulk while the surface presents a lower shear resistance than the amorphous films deposited at TS = 20°C with PN2 = 0 and 0.5 mTorr. In addition, the low average roughness in the track during the start of the wear test helps observation of the low wear behavior because it prevents tip-asperity interactions that could lead to peelingoff of surface material, which would contribute to wear.…”

Structure and Characterization of Vacuum Arc Deposited Carbon Films—A Critical Overview

“…Due to the weak interaction between neighbored graphene layers, they have a much higher compressibility in this direction in comparison to the high stiffness of the covalent bonds within the layer. For carbon layers, deposited by vacuum arcs above around 200 °C, the formation of the curved graphene ribbons perpendicular to the surface has been clearly proved by TEM investigations and by electron diffraction [40,70,[90][91][92][93][94]. The perpendicular orientation occurs also at inclined incidence of the carbon ions under 45° or 65° [46] or 70° [95].…”