Tribological properties of DLC nanolayer on Si prepared by plasma-based ion implantation

Diamond-like carbon nanofilm was prepared on single crystal Si wafer by plasma-based ion implantation (PBII). The friction and wear properties of the resulting DLC film sliding against Si₃N₄ ball at various loads and velocities were measured on a universal reciprocating friction and wear tester, and the wear track morphologies were observed on a scanning electron microscope. It was found that a smooth and compact diamond-like carbon film with a thickness below 40 nm was formed on the Si surface by the PBII, which contributed to significantly improving the friction and wear behavior of the Si substrate. The excellent wear resistance of the DLC film conformed well to its wear track morphology as well. Namely, the DLC film was characterized by slight adhesion and scuffing as it slid against the ceramic ball even at a large load of 4 N, but the bare Si substrate was dominated by severe adhesion and scuffing even at a load as small as 0.5 N. Moreover, the friction coefficient and life of the DLC film decreased considerably with increasing load or sliding velocity, which was attributed to the strengthened graphitization of the DLC film thereat.