In this study, the nucleation mechanism of carbon nanocones is investigated using molecular dynamics (MD) simulations and structural analyses and is compared with that of carbon nanotubes. It is shown that the structural stability of carbon nanocones is sensitive to the cone apex angle. Specifically, an increase in the conical angle results in a moderate improvement in the structural stability of the nanocone as a result of a lower strain energy in the capped mantle. The simulation results also show that the melting temperature of the nanocone increases with increasing conical angle. Furthermore, it is observed that a metastable tube-like structure is formed in carbon nanocones with a lower conical angle at temperatures ranging from 2400 to 3600 K. Finally, the numerical simulations reveal that the mechanical properties of carbon nanocones under nanoindentation are strongly dependent on the conical angle. For carbon nanocones with a large conical angle, the high deformation-promoted reactivity and reversible mechanical response have been performed due to highly symmetrical networks.

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An experimental investigation was performed on the coefficients of friction (COFs) and wear properties of pure water and oil-in-water (O/W) working fluids containing carbon nanocapsules (CNCs) with concentrations ranging from 0 to 1.0 wt.%. For the O/W working fluid, the ratio of oil to water was set as 6%. It was shown that for the water working fluid, the COF decreased by around 20% as the CNC content increased from 0 to 1.0 wt.%. In contrast, the wear volume increased by 50% as the CNC addition increased from 0 to 0.5 wt.%, but it fell to a value slightly lower than that achieved using only pure water (i.e., no CNCs) as the CNC content was further increased to 1.0 wt.%. For the O/W emulsion, the addition of 0.8 wt.% CNCs reduced the COF by around 30% compared to that of the emulsion with no CNCs. Overall, the results showed that while the addition of a small quantity (6%) of oil to the water working fluid had a relatively small effect on the wear performance, the addition of an appropriate quantity of CNCs (i.e., 0.8 wt.%) resulted in a significantly lower COF and an improved wear surface.