The diamond-like carbon (DLC) films were prepared from methane, benzene and toluene by thermal electron exited plasma CVD method. Micro-laser Raman analysis of three films showed a typical spectrum of DLC film. The hardness and hydrogen content of the film were 11−25 GPa and 23−29 at%, respectively. The tribological properties of three DLC films were investigated using a scratch tester, a Bowden-Leben type friction tester and a ball-on-disk type reciprocating friction tester. The effects of raw materials on the tribological properties were confirmed. The difference in tribological properties of these three films seems to be related with their hardness. That is, the friction coefficient of the DLC film with low hardness was lower than that of the film with high hardness. On the other hand, when the hardness was increased, the specific wear rate of the DLC films appeared to decrease. The transferred films formed on mating material surfaces are supposed to play significant roles in the tribological properties of the DLC films.
