Mechanical and tribological properties of non-hydrogenated DLC films synthesized by IBAD

Diamond-like carbon (DLC) films have been deposited on Si(100) substrates by an ion beam assisted deposition (IBAD) system. The effect of ion bombardment energy on surface roughness, mechanical and tribological properties of the DLC films has been studied over the ion bombardment energy range of 100–800 eV. The measured results of atomic force microscopy (AFM) showed that the DLC films are very smooth and the surface roughness is lower than that of the Si substrate at certain ion bombardment energy. Elasticity and nanohardness of the DLC films were studied by a nanoindentation technique. From nanoindentation load-displacement curves, it was concluded that most of the DLC films have high elasticity. Comparing the nanohardness with the conventional knoop microhardness of the same series of samples, we saw that the values of knoop microhardness are much higher than those of nanohardness. The correlation of the sp3 bond fraction in the films estimated from Raman spectroscopy with surface roughness, elasticity and hardness has been established. Tribological behavior of the DLC films sliding against the ZrO2 ball was evaluated using a pin-on-disk tribometer. It was found that the surface roughness and the hardness have an effect on the friction coefficients.