By combining vapor deposition of organic compounds and simultaneous energetic Ar₊ion irradiation, carbonaceous films were deposited onto substrates of a bearing steel (SUJ2). The organic compounds were benzene, pentaphenylether, poly-(dimethylsiloxane) and pentaphenyl-trimethyl-trisiloxane.
All the carbonaceous films produced were amorphous and showed low coefficient of friction less than 0.2 in ambient atmosphere. In particular, the films produced from the siloxane compounds (ion-irradiated silicone films) showed extremely low coefficient of friction less than 0.05. Furthermore, the friction coefficient of the ion-irradiated silicone films was much less sensitive to moisture compared to diamond-like carbon films prepared by plasma-enhanced chemical vapor deposition.
Scanning electron microscopy and electron-probe micro-analysis for the pins of SUJ2 revealed that the ion-irradiated silicone films are easily transferred to the surface of the pin during sliding. This fact may be related with the very low friction coefficient for the ion-irradiated silicone films.