Abstract
The low coefficient of friction and the high wear resistance of DLC coatings is usually attributed to a transfer film on the counter part and a phase transformation within the coating. In ball indentation, sliding and rolling contact experiments the formation of the transfer film, the phase transition and the wear and friction behaviour of a-C:H coatings was examined. The wear increased linear with the time and the initial roughness. The forming of the transfer film seems to be linear as well and is accompanied by a reduction of the sp3 content of the coating within the contact zone. Molecular dynamic simulation show, that the increase in sp2 portion in not due to a grafitisation of the a-C:H, but due to the forming of more amorphous sp2 bondings, which leads to a reduction of interatomic contacts to the counterpart.