Tribochemically Active Ti–C–S Nanocomposite Coatings

Abstract

We demonstrate a new concept of self-adaptive materials, where sulphur is incorporated into TiC/a-C coatings and may be released in, for example, a tribological contact. By reactive sputtering with H2S, sulphur goes into the carbide to form a TiCxSy phase in an amorphous carbon matrix. The addition of sulphur lowers the friction against steel. Significantly lower friction is obtained against a tungsten counter-surface, as WS2 is generated in the contact. Annealing experiments and formation energy calculations confirm that sulphur can be released from TiCxSy. Ti–C–S coatings are thus chemically active in tribological contacts, creating possibilities of new low-friction systems. © 2013 Jill Sundberg, Harald Nyberg, Erik Särhammar, Krisztina Kádas, Liping Wang, Olle Eriksson, Tomas Nyberg, Staffan Jacobson and Ulf Jansson.