Tribological behavior of silicon-incorporated diamond-like carbon films

The tribological behavior between silicon-incorporated diamond-like carbon (Si-DLC) films and a steel ball was investigated from the viewpoint of tribochemical reaction. The films were deposited on Si(100) wafers from radio-frequency glow discharge of mixtures of benzene and dilute silane gases. The tribological behavior was investigated by using a ball-on-disk type wear rig in ambient atmosphere. The variation of the friction coefficient with the number of contact cycles was compared among films having of various silicon concentrations from 0 to 9.5 at%. It was observed that the friction coefficient decreased with increasing silicon concentration in the films. Furthermore, the friction behavior became more stable even at a small amount of silicon less than 0.5 at% incorporated. By analyzing the composition of the debris formed, we could conclude that the low and stabilized friction coefficient is intimately related to the formation of the silicon-rich oxide debris. These results are consistent with a previously suggested mechanism that the hydrated silica debris results in the low friction coefficient in a humid environment. (C) 1999 Elsevier Science S.A. All rights reserved.