Synthesis, structure and mechanical properties of fullerene-like carbon nitride films deposited by DC magnetron sputtering

Carbon nitride (CNx) films were deposited by direct current magnetron sputtering at different N2 fractions and a substrate temperature of 450 °C. The composition and microstructure of CNx films were investigated by high resolution transmission electron microscopy, X-ray absorption near-edge spectroscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. The CNx films change from amorphous to fullerene-like nanostructure as the N2 fraction is ranged from 0.05 to 0.1, and then to nitridized graphite nanocrystals in amorphous matrix at pure N2, and the curvature of the basal planes decreases with the increase of N content in CNx films. Meanwhile, the structural analysis provides the identification of spectral signatures related with the formation and promotion of FL arrangements, and the formation of C-sp3 sites has been generally considered as the cross-linking path in fullerene-like CNx. Their mechanical and tribological properties were also investigated in detail, aiming at illustrating excellent mechanical, friction and wear behaviours of the fullerene-like CNx film with respect to its high hardness and elastic recovery and less dependence on humidity and oxygen as compared with the amorphous CNx film.