Growth and characterization of C-N thin films

Our preliminary studies showed that carbon nitride in amorphous and crystalline forms can be synthesized using reactive magnetron sputtering with substrates held at ambient temperatures. The films were evaluated by a wide range of diagnostic techniques (Auger spectroscopy, IR spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, atomic force microscopy, transmission electron microscopy and tribo-testing). The most important finding is that we can deposit smooth, continuous C-N films on a variety of substrates. Unlike previous work, we were able to incorporate significant amounts of nitrogen into these films (N:C ratio exceeding 0.4 in the bulk). More importantly, IR studies show that nitrogen exists not merely as gaseous species but is chemically bonded to carbon in the film. Transmission electron microscopy studies showed clearly the coexistence of amorphous and crystalline C-N phases. When deposited on polycrystalline zirconium substrates, these films appear to be very adherent and wear resistant under lubricated sliding conditions. In dry sliding against 52100 steels, carbon nitride gives friction coefficients as low as 0.16, comparable with that of diamond.