Synthesis and tribological properties of carbon nitride as a novel superhard coating and solid lubricant

This paper reports the discovery of a new crystalline thin-film material suitable for tribological applications. Carbon nitride thin films were synthesized using DC magnetron sputtering of a high-purity graphite target in an argon/nitrogen plasma using various substrates held at ambient temperatures. These thin films comist of mixed amorphous and crystalline phases. Unlike previous work, a significant amount of nitrogen, the NIC ratio exceeding 0.4 in the bulk, was incorporated. Infra-red studies showed that nitrogen was bonded to carbon in the film. These films appeared to be very wear-resistant under lubricated sliding conditiom. In dry sliding, carbon nitride gave friction coefficients as low as 0.16, comparable to diamond.