Pin-on-disk characterization of amorphous carbon films prepared by filtered cathodic vacuum arc technique

The frictional behaviour of tetrahedral amorphous carbon (ta-C) films, prep ared by filtered cathodic vacuum are (FCVA) technique, is characterised by a pin-on-disk tribometer. The influence of different test conditions, such as applied load, static sliding partners (steel, sapphire and silicon nitri de balls) and test environment (nitrogen, oxygen and low/high humidity), on the frictional behaviour of ta-C films was investigated. In general, a lower average coefficient of friction was observed with incre ase in applied load for all the different static partners. A lower coeffici ent of friction was obtained when the ta-C films slid against a sapphire ba ll, as compared to other ball materials under the same applied load. This m ay be due to the interfacial him, which strongly depends on the reactive sp ecies such as oxygen, hydrogen, etc. in the surrounding with sliding partne r. Ta-C films tested in an inert low humidity nitrogen environment recorded the lowest coefficient of friction. This shows the effect of tribochemical interaction of the gaseous species in the surrounding environment on the f rictional behaviour of the ta-C film. The influence of different humidity o n the frictional behaviour of the ta-C films was also investigated. A lower humidity leads to increased coefficient of friction. (C) 2000 Elsevier Sci ence S.A. All rights reserved.