Structure and properties of carbon onion layers deposited onto various substrates

Abstract

120 keV carbon ions implantations at high fluences (0.5–8×1017 ions cm−2) were performed at elevated temperature (⩾500 °C) in silver layers deposited on various substrates (Si (100), 304 L stainless steel, and pure fused silica). Spherical carbon onions (3–15 nm in diameter) were so produced in the silver layers. A pure carbon onion thin film deposited on the substrate was obtained after annealing in vacuum. Atomic force microscopy and high-resolution transmission electron microscopy experiments were performed to characterize the structure of the thin films. Optical transmittance spectra of carbon onion layers deposited onto silica substrates revealed two absorption peaks centered at 220–230 nm and at 265 nm that were attributed to the presence of carbon onions and residual disordered graphitic carbon, respectively. Tribological experiments performed on silver–carbon onions composite thin films revealed that the friction coefficient is close to that of a pure silver film (0.2) but with much better wear behavior.

Anti-wear and Friction Reducing Mechanisms of Carbon Nano-onions as Lubricant Additives

“…The p/p* excitation is centred at 6.1 eV for carbon nano- onions compared to 7 eV for graphite sheets. These data are in good agreement with values observed by Cabioc'h et al [18,19] on carbon onions with a p/p* peak at 5.7 eV and a plasmon loss peak maximum at 24 eV for a momentum transfer of 0.15 A -1 (corresponding nearly to our operating conditions). These significant differences are basically attributed to the curvature of sheets, the coupling of electrons on the spherical shells being well different from the coupling in the planar case.…”

Photoemission study of onionlike carbons produced by annealing nanodiamonds

“…Sufficient quantities could be produced for investigation of their optical, electronic and tribological properties. [14][15][16][17] These carbon onions were characterized by Fourier transform infrared ͑FTIR͒ spectroscopy 16 and it was shown that the most stable state for the onions consists of concentric spheres of fullerenes C n ͑n = 60, 240, …͒. Until now, the electronic properties of the onions were characterized only by spatially resolved EELS in transmission 15,18 and reflection mode.…”

The Role of Nickel in Ni-Containing Nanotubes and Onions as Lubricant Additives

“…Few studies on their tribological properties have been reported so far. Cabioc'h et al [3] studied the tribological properties of silver films containing carbon onions and observed an increase in the lifetime of the coatings when carbon onions are present. Their use as solid lubricant between a steel ball and a silicon wafer lead to a lower friction coefficient and a lower wear compared to graphite [4].…”