Abstract: Diamond-like carbon (DLC) films were prepared on Ti alloy substrate with an rf-plasma enhanced chemical vapor deposition method (rf PECVD), their nano-mechanical
properties were evaluated by using a Nano Indenter system with attachments of Continues Stiffness Measurement (CSM) and lateral force measurement (LFM).
The results show that the hardness of those films increases with film thickness, but their increment is small; during scratching, three processes containing fully
elastic recovery, asynchronous recovery of films and substrate, and delaminating of films, successively occur as the increase of load; at the first regime, no
damage could be found on the surface of films, in the second regime, the trace like fish bone formed; as the thickness of films increases, the critical load increases,
but the delamination of films is more severe, which may be attributed to the increase of internal stress in the films.

Key words: diamond-like carbon, nanoindentation, nanoscratch, biomaterials