Mechanical characterization and tribological evaluation of ion-beam-assisted sputter coatings of carbon with nitrogen incorporation

Sputter coatings of carbon with nitrogen incorporation have been prepared by ion-beam-assisted deposition on Si(111) substrates. An amorphous structure with tiny crystals in the coating has been observed and confirmed by field-emission transmission electron microscopy. Analyses by X-ray photoelectron spectroscopy and secondary-ion mass spectrometry have revealed that the level of nitrogen incorporation is about 10%, and the composition distribution of both carbon and nitrogen atoms normal to the coating surfaces is homogeneous. A detailed Raman analysis has further shown that the proportion of sp2 carbon bonds increases with the nitrogen acceleration energy. The influences of different nitrogen incorporation parameters and different coating thicknesses on the mechanical properties of carbon nitride coatings have been systematically characterized for the first time from the viewpoints of surface roughness, nanoindentation hardness and internal stress. Finally, the tribological properties of ion-beam-assisted carbon nitride coatings have also been evaluated in terms of nitrogen incorporation and coating thickness.