Analysis of nano-scratch behavior of diamond-like carbon films

The nano-scratch behavior of diamond-like carbon films prepared on Ti alloy substrates by r.f. PECVD was analyzed using a Nano Indenter® XP system with the attachment of lateral force measurement in order to understand the deformation mechanism of the films. It was concluded that the three processes that occur successively with the increase of load during the scratching are fully elastic recovery, plastic deformation, and delamination of the films. In the first regime, no damage could be found on the surface of the films. In the second regime, due to the asynchronous recovery of the films and the substrates, a trace-like fish bone composed of tiny cracks along the track of the indenter was formed. It was only in the third regime when the critical load was obtained that the partial spallation of the films was detected with careful examination. It was determined that the film spallation originated from the fish bone cracking, and the fish bone was just a profiling of the Berkovich indenter.