Structure–property relationship of Si-DLC films

In the present work, Ar+ ion beam assisted deposition was utilized at various ion energies and current densities to prepare silicon-containing diamond-like carbon (Si–DLC) films. TEM analysis showed that the films are mainly amorphous and composed of diamond-like and graphite-like domains. The bonding characteristics of the films were studied by FTIR spectroscopy. It was found that Si suppresses formation of aromatic structures and participates in the structure of DLC by tetrahedral bonding with H and CHn groups. A direct correspondence was determined between ion current density during deposition and the sp3/sp2 ratio in the films. Lower ion current densities were found to favor SiC tetrahedral bonds, increase sp3/sp2 ratio and hardness but also increase surface roughness and decrease deposition rate. Pin-on-disc experiments were conducted to characterize the tribological behavior of the Si–DLC films. In general, the films exhibited low friction and high wear resistance, especially under low loading conditions. The results suggest that films with a pronounced graphitic nature possess better tribological characteristics. Films with enhanced diamond-like character and of sufficient thickness may have potential for applications against ceramic counter faces.